-
Notifications
You must be signed in to change notification settings - Fork 62
Expand file tree
/
Copy pathcustom_cmap.html
More file actions
389 lines (342 loc) · 64.6 KB
/
Copy pathcustom_cmap.html
File metadata and controls
389 lines (342 loc) · 64.6 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="X-UA-Compatible" content="IE=Edge" />
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Creating a colormap from a list of colors — Matplotlib 3.3.1 documentation</title>
<link rel="stylesheet" href="../../_static/mpl.css?v3.3.1-2-ge49322daa" type="text/css" />
<link rel="stylesheet" href="../../_static/pygments.css" type="text/css" />
<link rel="stylesheet" type="text/css" href="../../_static/graphviz.css" />
<link rel="stylesheet" type="text/css" href="../../_static/copybutton.css" />
<link rel="stylesheet" type="text/css" href="../../_static/gallery.css" />
<link rel="stylesheet" type="text/css" href="../../_static/gallery-binder.css" />
<link rel="stylesheet" type="text/css" href="../../_static/gallery-dataframe.css" />
<script id="documentation_options" data-url_root="../../" src="../../_static/documentation_options.js"></script>
<script src="../../_static/jquery.js"></script>
<script src="../../_static/underscore.js"></script>
<script src="../../_static/doctools.js"></script>
<script src="../../_static/language_data.js"></script>
<script src="../../_static/clipboard.min.js"></script>
<script src="../../_static/copybutton.js"></script>
<script async="async" src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.7/latest.js?config=TeX-AMS-MML_HTMLorMML"></script>
<link rel="search" type="application/opensearchdescription+xml"
title="Search within Matplotlib 3.3.1 documentation"
href="../../_static/opensearch.xml"/>
<link rel="shortcut icon" href="../../_static/favicon.ico"/>
<link rel="index" title="Index" href="../../genindex.html" />
<link rel="search" title="Search" href="../../search.html" />
<link rel="top" title="Matplotlib 3.3.1 documentation" href="#" />
<link rel="canonical" href="https://matplotlib.org/stable/gallery/color/custom_cmap.html" />
<link rel="stylesheet" href="../../_static/custom.css" type="text/css" />
<meta name="viewport" content="width=device-width, initial-scale=0.9, maximum-scale=0.9" />
<script data-domain="matplotlib.org" defer="defer" src="https://views.scientific-python.org/js/script.js"></script>
</head><body>
<div id="unreleased-message"> You are reading an old version of the documentation (v3.3.1). For the latest version see <a href="https://matplotlib.org/stable/gallery/color/custom_cmap.html">https://matplotlib.org/stable/gallery/color/custom_cmap.html</a></div>
<!--
<div id="annc-banner">
</div>
-->
<div style="background-color: white; text-align: left; padding: 10px 10px 15px 15px; position: relative;">
<a href="../../index.html">
<div style="float: left; position: absolute; width: 496px; bottom: 0; padding-bottom: 24px"><span style="float: right; color: #789; background: white">Version 3.3.1</span></div>
<img src="../../_static/logo2_compressed.svg" height="125px" border="0" alt="matplotlib"/></a>
<!-- The "Fork me on github" ribbon -->
<div id="forkongithub"><a href="https://github.com/matplotlib/matplotlib">Fork me on GitHub</a></div>
</div>
<nav class="main-nav">
<ul>
<li><a href="../../users/installing.html">Installation</a></li>
<li><a href="../../contents.html">Documentation</a></li>
<li><a href="../index.html">Examples</a></li>
<li><a href="../../tutorials/index.html">Tutorials</a></li>
<li><a href="../../devel/index.html">Contributing</a></li>
<li class="nav-right">
<form class="search" action="../../search.html" method="get">
<input type="text" name="q" aria-labelledby="searchlabel" placeholder="Search"/>
</form>
</li>
</ul>
</nav>
<div class="related" role="navigation" aria-label="related navigation">
<h3>Navigation</h3>
<ul>
<li class="right" style="margin-right: 10px">
<a href="../../genindex.html" title="General Index"
accesskey="I">index</a></li>
<li class="right" >
<a href="../../py-modindex.html" title="Python Module Index"
>modules</a> |</li>
<li><a href="../../index.html">home</a>| </li>
<li><a href="../../contents.html">contents</a> »</li>
<li class="nav-item nav-item-this"><a href="">Creating a colormap from a list of colors</a></li>
</ul>
</div>
<div class="sphinxsidebar" role="navigation" aria-label="main navigation">
<div class="sphinxsidebarwrapper">
<h3><a href="../../contents.html">Table of Contents</a></h3>
<ul>
<li><a class="reference internal" href="#">Creating a colormap from a list of colors</a><ul>
<li><a class="reference internal" href="#creating-custom-colormaps">Creating custom colormaps</a><ul>
<li><a class="reference internal" href="#references">References</a></li>
</ul>
</li>
</ul>
</li>
</ul>
<div class="relations">
<h3>Related Topics</h3>
<ul>
<li><a href="../../contents.html">Documentation overview</a><ul>
</ul></li>
</ul>
</div>
<div id="sidebar-pagesource" role="note" aria-label="source link"
style="margin-top: 1.5em; padding-top: 0.1em; border-top: 1px solid #86989b">
<a href="../../_sources/gallery/color/custom_cmap.rst.txt"
style="color: #c0c0c0" rel="nofollow">Show Page Source</a>
</div>
</div>
</div>
<div class="document">
<div class="documentwrapper">
<div class="bodywrapper">
<div class="body" role="main">
<div class="sphx-glr-download-link-note admonition note">
<p class="first admonition-title">Note</p>
<p class="last">Click <a class="reference internal" href="#sphx-glr-download-gallery-color-custom-cmap-py"><span class="std std-ref">here</span></a> to download the full example code</p>
</div>
<div class="sphx-glr-example-title section" id="creating-a-colormap-from-a-list-of-colors">
<span id="sphx-glr-gallery-color-custom-cmap-py"></span><h1>Creating a colormap from a list of colors<a class="headerlink" href="#creating-a-colormap-from-a-list-of-colors" title="Permalink to this headline">¶</a></h1>
<p>For more detail on creating and manipulating colormaps see
<a class="reference internal" href="../../tutorials/colors/colormap-manipulation.html"><span class="doc">Creating Colormaps in Matplotlib</span></a>.</p>
<p>Creating a <a class="reference internal" href="../../tutorials/colors/colormaps.html"><span class="doc">colormap</span></a> from a list of colors
can be done with the <a class="reference internal" href="../../api/_as_gen/matplotlib.colors.LinearSegmentedColormap.html#matplotlib.colors.LinearSegmentedColormap.from_list" title="matplotlib.colors.LinearSegmentedColormap.from_list"><code class="xref py py-obj docutils literal notranslate"><span class="pre">LinearSegmentedColormap.from_list</span></code></a> method. You must
pass a list of RGB tuples that define the mixture of colors from 0 to 1.</p>
<div class="section" id="creating-custom-colormaps">
<h2>Creating custom colormaps<a class="headerlink" href="#creating-custom-colormaps" title="Permalink to this headline">¶</a></h2>
<p>It is also possible to create a custom mapping for a colormap. This is
accomplished by creating dictionary that specifies how the RGB channels
change from one end of the cmap to the other.</p>
<p>Example: suppose you want red to increase from 0 to 1 over the bottom
half, green to do the same over the middle half, and blue over the top
half. Then you would use:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">cdict</span> <span class="o">=</span> <span class="p">{</span><span class="s1">'red'</span><span class="p">:</span> <span class="p">((</span><span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">),</span>
<span class="p">(</span><span class="mf">0.5</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">),</span>
<span class="p">(</span><span class="mf">1.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">)),</span>
<span class="s1">'green'</span><span class="p">:</span> <span class="p">((</span><span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">),</span>
<span class="p">(</span><span class="mf">0.25</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">),</span>
<span class="p">(</span><span class="mf">0.75</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">),</span>
<span class="p">(</span><span class="mf">1.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">)),</span>
<span class="s1">'blue'</span><span class="p">:</span> <span class="p">((</span><span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">),</span>
<span class="p">(</span><span class="mf">0.5</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">),</span>
<span class="p">(</span><span class="mf">1.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">))}</span>
</pre></div>
</div>
<p>If, as in this example, there are no discontinuities in the r, g, and b
components, then it is quite simple: the second and third element of
each tuple, above, is the same--call it "y". The first element ("x")
defines interpolation intervals over the full range of 0 to 1, and it
must span that whole range. In other words, the values of x divide the
0-to-1 range into a set of segments, and y gives the end-point color
values for each segment.</p>
<p>Now consider the green. cdict['green'] is saying that for
0 <= x <= 0.25, y is zero; no green.
0.25 < x <= 0.75, y varies linearly from 0 to 1.
x > 0.75, y remains at 1, full green.</p>
<p>If there are discontinuities, then it is a little more complicated.
Label the 3 elements in each row in the cdict entry for a given color as
(x, y0, y1). Then for values of x between x[i] and x[i+1] the color
value is interpolated between y1[i] and y0[i+1].</p>
<p>Going back to the cookbook example, look at cdict['red']; because y0 !=
y1, it is saying that for x from 0 to 0.5, red increases from 0 to 1,
but then it jumps down, so that for x from 0.5 to 1, red increases from
0.7 to 1. Green ramps from 0 to 1 as x goes from 0 to 0.5, then jumps
back to 0, and ramps back to 1 as x goes from 0.5 to 1.:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">row</span> <span class="n">i</span><span class="p">:</span> <a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">x</span></a> <span class="n">y0</span> <span class="n">y1</span>
<span class="o">/</span>
<span class="o">/</span>
<span class="n">row</span> <span class="n">i</span><span class="o">+</span><span class="mi">1</span><span class="p">:</span> <a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">x</span></a> <span class="n">y0</span> <span class="n">y1</span>
</pre></div>
</div>
<p>Above is an attempt to show that for x in the range x[i] to x[i+1], the
interpolation is between y1[i] and y0[i+1]. So, y0[0] and y1[-1] are
never used.</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">numpy</span> <span class="k">as</span> <span class="nn">np</span>
<span class="kn">import</span> <span class="nn">matplotlib.pyplot</span> <span class="k">as</span> <span class="nn">plt</span>
<span class="kn">from</span> <span class="nn">matplotlib.colors</span> <span class="kn">import</span> <a href="../../api/_as_gen/matplotlib.colors.LinearSegmentedColormap.html#matplotlib.colors.LinearSegmentedColormap" title="matplotlib.colors.LinearSegmentedColormap" class="sphx-glr-backref-module-matplotlib-colors sphx-glr-backref-type-py-class"><span class="n">LinearSegmentedColormap</span></a>
<span class="c1"># Make some illustrative fake data:</span>
<a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">x</span></a> <span class="o">=</span> <a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.arange.html#numpy.arange" title="numpy.arange" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-function"><span class="n">np</span><span class="o">.</span><span class="n">arange</span></a><span class="p">(</span><span class="mi">0</span><span class="p">,</span> <a href="https://docs.python.org/3/library/functions.html#float" title="builtins.float" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">np</span><span class="o">.</span><span class="n">pi</span></a><span class="p">,</span> <span class="mf">0.1</span><span class="p">)</span>
<a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">y</span></a> <span class="o">=</span> <a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.arange.html#numpy.arange" title="numpy.arange" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-function"><span class="n">np</span><span class="o">.</span><span class="n">arange</span></a><span class="p">(</span><span class="mi">0</span><span class="p">,</span> <span class="mi">2</span> <span class="o">*</span> <a href="https://docs.python.org/3/library/functions.html#float" title="builtins.float" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">np</span><span class="o">.</span><span class="n">pi</span></a><span class="p">,</span> <span class="mf">0.1</span><span class="p">)</span>
<a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">X</span></a><span class="p">,</span> <a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">Y</span></a> <span class="o">=</span> <a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.meshgrid.html#numpy.meshgrid" title="numpy.meshgrid" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-function"><span class="n">np</span><span class="o">.</span><span class="n">meshgrid</span></a><span class="p">(</span><a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">x</span></a><span class="p">,</span> <a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">y</span></a><span class="p">)</span>
<a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">Z</span></a> <span class="o">=</span> <a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.cos.html#numpy.cos" title="numpy.cos" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-data"><span class="n">np</span><span class="o">.</span><span class="n">cos</span></a><span class="p">(</span><a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">X</span></a><span class="p">)</span> <span class="o">*</span> <a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.sin.html#numpy.sin" title="numpy.sin" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-data"><span class="n">np</span><span class="o">.</span><span class="n">sin</span></a><span class="p">(</span><a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">Y</span></a><span class="p">)</span> <span class="o">*</span> <span class="mi">10</span>
</pre></div>
</div>
<p>--- Colormaps from a list ---</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><a href="https://docs.python.org/3/library/stdtypes.html#list" title="builtins.list" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">colors</span></a> <span class="o">=</span> <span class="p">[(</span><span class="mi">1</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">0</span><span class="p">),</span> <span class="p">(</span><span class="mi">0</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">0</span><span class="p">),</span> <span class="p">(</span><span class="mi">0</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">1</span><span class="p">)]</span> <span class="c1"># R -> G -> B</span>
<a href="https://docs.python.org/3/library/stdtypes.html#list" title="builtins.list" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">n_bins</span></a> <span class="o">=</span> <span class="p">[</span><span class="mi">3</span><span class="p">,</span> <span class="mi">6</span><span class="p">,</span> <span class="mi">10</span><span class="p">,</span> <span class="mi">100</span><span class="p">]</span> <span class="c1"># Discretizes the interpolation into bins</span>
<a href="https://docs.python.org/3/library/stdtypes.html#str" title="builtins.str" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">cmap_name</span></a> <span class="o">=</span> <span class="s1">'my_list'</span>
<a href="../../api/_as_gen/matplotlib.figure.Figure.html#matplotlib.figure.Figure" title="matplotlib.figure.Figure" class="sphx-glr-backref-module-matplotlib-figure sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">fig</span></a><span class="p">,</span> <a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">axs</span></a> <span class="o">=</span> <a href="../../api/_as_gen/matplotlib.pyplot.subplots.html#matplotlib.pyplot.subplots" title="matplotlib.pyplot.subplots" class="sphx-glr-backref-module-matplotlib-pyplot sphx-glr-backref-type-py-function"><span class="n">plt</span><span class="o">.</span><span class="n">subplots</span></a><span class="p">(</span><span class="mi">2</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="n">figsize</span><span class="o">=</span><span class="p">(</span><span class="mi">6</span><span class="p">,</span> <span class="mi">9</span><span class="p">))</span>
<a href="../../api/_as_gen/matplotlib.figure.Figure.html#matplotlib.figure.Figure.subplots_adjust" title="matplotlib.figure.Figure.subplots_adjust" class="sphx-glr-backref-module-matplotlib-figure sphx-glr-backref-type-py-method"><span class="n">fig</span><span class="o">.</span><span class="n">subplots_adjust</span></a><span class="p">(</span><span class="n">left</span><span class="o">=</span><span class="mf">0.02</span><span class="p">,</span> <span class="n">bottom</span><span class="o">=</span><span class="mf">0.06</span><span class="p">,</span> <span class="n">right</span><span class="o">=</span><span class="mf">0.95</span><span class="p">,</span> <span class="n">top</span><span class="o">=</span><span class="mf">0.94</span><span class="p">,</span> <span class="n">wspace</span><span class="o">=</span><span class="mf">0.05</span><span class="p">)</span>
<span class="k">for</span> <a href="https://docs.python.org/3/library/functions.html#int" title="builtins.int" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">n_bin</span></a><span class="p">,</span> <span class="n">ax</span> <span class="ow">in</span> <span class="nb">zip</span><span class="p">(</span><a href="https://docs.python.org/3/library/stdtypes.html#list" title="builtins.list" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">n_bins</span></a><span class="p">,</span> <a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">axs</span></a><span class="o">.</span><span class="n">ravel</span><span class="p">()):</span>
<span class="c1"># Create the colormap</span>
<a href="../../api/_as_gen/matplotlib.colors.LinearSegmentedColormap.html#matplotlib.colors.LinearSegmentedColormap" title="matplotlib.colors.LinearSegmentedColormap" class="sphx-glr-backref-module-matplotlib-colors sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">cm</span></a> <span class="o">=</span> <a href="../../api/_as_gen/matplotlib.colors.LinearSegmentedColormap.html#matplotlib.colors.LinearSegmentedColormap.from_list" title="matplotlib.colors.LinearSegmentedColormap.from_list" class="sphx-glr-backref-module-matplotlib-colors-LinearSegmentedColormap sphx-glr-backref-type-py-method"><span class="n">LinearSegmentedColormap</span><span class="o">.</span><span class="n">from_list</span></a><span class="p">(</span><a href="https://docs.python.org/3/library/stdtypes.html#str" title="builtins.str" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">cmap_name</span></a><span class="p">,</span> <a href="https://docs.python.org/3/library/stdtypes.html#list" title="builtins.list" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">colors</span></a><span class="p">,</span> <span class="n">N</span><span class="o">=</span><a href="https://docs.python.org/3/library/functions.html#int" title="builtins.int" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">n_bin</span></a><span class="p">)</span>
<span class="c1"># Fewer bins will result in "coarser" colomap interpolation</span>
<a href="../../api/image_api.html#matplotlib.image.AxesImage" title="matplotlib.image.AxesImage" class="sphx-glr-backref-module-matplotlib-image sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">im</span></a> <span class="o">=</span> <a href="../../api/_as_gen/matplotlib.axes.Axes.imshow.html#matplotlib.axes.Axes.imshow" title="matplotlib.axes.Axes.imshow" class="sphx-glr-backref-module-matplotlib-axes sphx-glr-backref-type-py-method"><span class="n">ax</span><span class="o">.</span><span class="n">imshow</span></a><span class="p">(</span><a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">Z</span></a><span class="p">,</span> <span class="n">origin</span><span class="o">=</span><span class="s1">'lower'</span><span class="p">,</span> <a href="../../api/_as_gen/matplotlib.colors.LinearSegmentedColormap.html#matplotlib.colors.LinearSegmentedColormap" title="matplotlib.colors.LinearSegmentedColormap" class="sphx-glr-backref-module-matplotlib-colors sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">cmap</span></a><span class="o">=</span><a href="../../api/_as_gen/matplotlib.colors.LinearSegmentedColormap.html#matplotlib.colors.LinearSegmentedColormap" title="matplotlib.colors.LinearSegmentedColormap" class="sphx-glr-backref-module-matplotlib-colors sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">cm</span></a><span class="p">)</span>
<a href="../../api/_as_gen/matplotlib.axes.Axes.set_title.html#matplotlib.axes.Axes.set_title" title="matplotlib.axes.Axes.set_title" class="sphx-glr-backref-module-matplotlib-axes sphx-glr-backref-type-py-method"><span class="n">ax</span><span class="o">.</span><span class="n">set_title</span></a><span class="p">(</span><span class="s2">"N bins: </span><span class="si">%s</span><span class="s2">"</span> <span class="o">%</span> <a href="https://docs.python.org/3/library/functions.html#int" title="builtins.int" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">n_bin</span></a><span class="p">)</span>
<a href="../../api/_as_gen/matplotlib.figure.Figure.html#matplotlib.figure.Figure.colorbar" title="matplotlib.figure.Figure.colorbar" class="sphx-glr-backref-module-matplotlib-figure sphx-glr-backref-type-py-method"><span class="n">fig</span><span class="o">.</span><span class="n">colorbar</span></a><span class="p">(</span><a href="../../api/image_api.html#matplotlib.image.AxesImage" title="matplotlib.image.AxesImage" class="sphx-glr-backref-module-matplotlib-image sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">im</span></a><span class="p">,</span> <span class="n">ax</span><span class="o">=</span><span class="n">ax</span><span class="p">)</span>
</pre></div>
</div>
<img alt="N bins: 3, N bins: 6, N bins: 10, N bins: 100" class="sphx-glr-single-img" src="../../_images/sphx_glr_custom_cmap_001.png" />
<p>--- Custom colormaps ---</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><a href="https://docs.python.org/3/library/stdtypes.html#dict" title="builtins.dict" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">cdict1</span></a> <span class="o">=</span> <span class="p">{</span><span class="s1">'red'</span><span class="p">:</span> <span class="p">((</span><span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">),</span>
<span class="p">(</span><span class="mf">0.5</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.1</span><span class="p">),</span>
<span class="p">(</span><span class="mf">1.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">)),</span>
<span class="s1">'green'</span><span class="p">:</span> <span class="p">((</span><span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">),</span>
<span class="p">(</span><span class="mf">1.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)),</span>
<span class="s1">'blue'</span><span class="p">:</span> <span class="p">((</span><span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">),</span>
<span class="p">(</span><span class="mf">0.5</span><span class="p">,</span> <span class="mf">0.1</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">),</span>
<span class="p">(</span><span class="mf">1.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">))</span>
<span class="p">}</span>
<a href="https://docs.python.org/3/library/stdtypes.html#dict" title="builtins.dict" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">cdict2</span></a> <span class="o">=</span> <span class="p">{</span><span class="s1">'red'</span><span class="p">:</span> <span class="p">((</span><span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">),</span>
<span class="p">(</span><span class="mf">0.5</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">),</span>
<span class="p">(</span><span class="mf">1.0</span><span class="p">,</span> <span class="mf">0.1</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">)),</span>
<span class="s1">'green'</span><span class="p">:</span> <span class="p">((</span><span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">),</span>
<span class="p">(</span><span class="mf">1.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)),</span>
<span class="s1">'blue'</span><span class="p">:</span> <span class="p">((</span><span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.1</span><span class="p">),</span>
<span class="p">(</span><span class="mf">0.5</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">),</span>
<span class="p">(</span><span class="mf">1.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">))</span>
<span class="p">}</span>
<a href="https://docs.python.org/3/library/stdtypes.html#dict" title="builtins.dict" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">cdict3</span></a> <span class="o">=</span> <span class="p">{</span><span class="s1">'red'</span><span class="p">:</span> <span class="p">((</span><span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">),</span>
<span class="p">(</span><span class="mf">0.25</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">),</span>
<span class="p">(</span><span class="mf">0.5</span><span class="p">,</span> <span class="mf">0.8</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">),</span>
<span class="p">(</span><span class="mf">0.75</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">),</span>
<span class="p">(</span><span class="mf">1.0</span><span class="p">,</span> <span class="mf">0.4</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">)),</span>
<span class="s1">'green'</span><span class="p">:</span> <span class="p">((</span><span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">),</span>
<span class="p">(</span><span class="mf">0.25</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">),</span>
<span class="p">(</span><span class="mf">0.5</span><span class="p">,</span> <span class="mf">0.9</span><span class="p">,</span> <span class="mf">0.9</span><span class="p">),</span>
<span class="p">(</span><span class="mf">0.75</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">),</span>
<span class="p">(</span><span class="mf">1.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)),</span>
<span class="s1">'blue'</span><span class="p">:</span> <span class="p">((</span><span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.4</span><span class="p">),</span>
<span class="p">(</span><span class="mf">0.25</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">),</span>
<span class="p">(</span><span class="mf">0.5</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">,</span> <span class="mf">0.8</span><span class="p">),</span>
<span class="p">(</span><span class="mf">0.75</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">),</span>
<span class="p">(</span><span class="mf">1.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">))</span>
<span class="p">}</span>
<span class="c1"># Make a modified version of cdict3 with some transparency</span>
<span class="c1"># in the middle of the range.</span>
<a href="https://docs.python.org/3/library/stdtypes.html#dict" title="builtins.dict" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">cdict4</span></a> <span class="o">=</span> <span class="p">{</span><span class="o">**</span><a href="https://docs.python.org/3/library/stdtypes.html#dict" title="builtins.dict" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">cdict3</span></a><span class="p">,</span>
<span class="s1">'alpha'</span><span class="p">:</span> <span class="p">((</span><span class="mf">0.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">),</span>
<span class="c1"># (0.25, 1.0, 1.0),</span>
<span class="p">(</span><span class="mf">0.5</span><span class="p">,</span> <span class="mf">0.3</span><span class="p">,</span> <span class="mf">0.3</span><span class="p">),</span>
<span class="c1"># (0.75, 1.0, 1.0),</span>
<span class="p">(</span><span class="mf">1.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">)),</span>
<span class="p">}</span>
</pre></div>
</div>
<p>Now we will use this example to illustrate 2 ways of
handling custom colormaps.
First, the most direct and explicit:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><a href="../../api/_as_gen/matplotlib.colors.LinearSegmentedColormap.html#matplotlib.colors.LinearSegmentedColormap" title="matplotlib.colors.LinearSegmentedColormap" class="sphx-glr-backref-module-matplotlib-colors sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">blue_red1</span></a> <span class="o">=</span> <a href="../../api/_as_gen/matplotlib.colors.LinearSegmentedColormap.html#matplotlib.colors.LinearSegmentedColormap" title="matplotlib.colors.LinearSegmentedColormap" class="sphx-glr-backref-module-matplotlib-colors sphx-glr-backref-type-py-class"><span class="n">LinearSegmentedColormap</span></a><span class="p">(</span><span class="s1">'BlueRed1'</span><span class="p">,</span> <a href="https://docs.python.org/3/library/stdtypes.html#dict" title="builtins.dict" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">cdict1</span></a><span class="p">)</span>
</pre></div>
</div>
<p>Second, create the map explicitly and register it.
Like the first method, this method works with any kind
of Colormap, not just
a LinearSegmentedColormap:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><a href="../../api/_as_gen/matplotlib.colors.LinearSegmentedColormap.html#matplotlib.colors.LinearSegmentedColormap" title="matplotlib.colors.LinearSegmentedColormap" class="sphx-glr-backref-module-matplotlib-colors sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">blue_red2</span></a> <span class="o">=</span> <a href="../../api/_as_gen/matplotlib.colors.LinearSegmentedColormap.html#matplotlib.colors.LinearSegmentedColormap" title="matplotlib.colors.LinearSegmentedColormap" class="sphx-glr-backref-module-matplotlib-colors sphx-glr-backref-type-py-class"><span class="n">LinearSegmentedColormap</span></a><span class="p">(</span><span class="s1">'BlueRed2'</span><span class="p">,</span> <a href="https://docs.python.org/3/library/stdtypes.html#dict" title="builtins.dict" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">cdict2</span></a><span class="p">)</span>
<span class="n">plt</span><span class="o">.</span><span class="n">register_cmap</span><span class="p">(</span><a href="../../api/_as_gen/matplotlib.colors.LinearSegmentedColormap.html#matplotlib.colors.LinearSegmentedColormap" title="matplotlib.colors.LinearSegmentedColormap" class="sphx-glr-backref-module-matplotlib-colors sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">cmap</span></a><span class="o">=</span><a href="../../api/_as_gen/matplotlib.colors.LinearSegmentedColormap.html#matplotlib.colors.LinearSegmentedColormap" title="matplotlib.colors.LinearSegmentedColormap" class="sphx-glr-backref-module-matplotlib-colors sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">blue_red2</span></a><span class="p">)</span>
<span class="n">plt</span><span class="o">.</span><span class="n">register_cmap</span><span class="p">(</span><a href="../../api/_as_gen/matplotlib.colors.LinearSegmentedColormap.html#matplotlib.colors.LinearSegmentedColormap" title="matplotlib.colors.LinearSegmentedColormap" class="sphx-glr-backref-module-matplotlib-colors sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">cmap</span></a><span class="o">=</span><a href="../../api/_as_gen/matplotlib.colors.LinearSegmentedColormap.html#matplotlib.colors.LinearSegmentedColormap" title="matplotlib.colors.LinearSegmentedColormap" class="sphx-glr-backref-module-matplotlib-colors sphx-glr-backref-type-py-class"><span class="n">LinearSegmentedColormap</span></a><span class="p">(</span><span class="s1">'BlueRed3'</span><span class="p">,</span> <a href="https://docs.python.org/3/library/stdtypes.html#dict" title="builtins.dict" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">cdict3</span></a><span class="p">))</span>
<span class="n">plt</span><span class="o">.</span><span class="n">register_cmap</span><span class="p">(</span><a href="../../api/_as_gen/matplotlib.colors.LinearSegmentedColormap.html#matplotlib.colors.LinearSegmentedColormap" title="matplotlib.colors.LinearSegmentedColormap" class="sphx-glr-backref-module-matplotlib-colors sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">cmap</span></a><span class="o">=</span><a href="../../api/_as_gen/matplotlib.colors.LinearSegmentedColormap.html#matplotlib.colors.LinearSegmentedColormap" title="matplotlib.colors.LinearSegmentedColormap" class="sphx-glr-backref-module-matplotlib-colors sphx-glr-backref-type-py-class"><span class="n">LinearSegmentedColormap</span></a><span class="p">(</span><span class="s1">'BlueRedAlpha'</span><span class="p">,</span> <a href="https://docs.python.org/3/library/stdtypes.html#dict" title="builtins.dict" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">cdict4</span></a><span class="p">))</span>
</pre></div>
</div>
<p>Make the figure:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><a href="../../api/_as_gen/matplotlib.figure.Figure.html#matplotlib.figure.Figure" title="matplotlib.figure.Figure" class="sphx-glr-backref-module-matplotlib-figure sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">fig</span></a><span class="p">,</span> <a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">axs</span></a> <span class="o">=</span> <a href="../../api/_as_gen/matplotlib.pyplot.subplots.html#matplotlib.pyplot.subplots" title="matplotlib.pyplot.subplots" class="sphx-glr-backref-module-matplotlib-pyplot sphx-glr-backref-type-py-function"><span class="n">plt</span><span class="o">.</span><span class="n">subplots</span></a><span class="p">(</span><span class="mi">2</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="n">figsize</span><span class="o">=</span><span class="p">(</span><span class="mi">6</span><span class="p">,</span> <span class="mi">9</span><span class="p">))</span>
<a href="../../api/_as_gen/matplotlib.figure.Figure.html#matplotlib.figure.Figure.subplots_adjust" title="matplotlib.figure.Figure.subplots_adjust" class="sphx-glr-backref-module-matplotlib-figure sphx-glr-backref-type-py-method"><span class="n">fig</span><span class="o">.</span><span class="n">subplots_adjust</span></a><span class="p">(</span><span class="n">left</span><span class="o">=</span><span class="mf">0.02</span><span class="p">,</span> <span class="n">bottom</span><span class="o">=</span><span class="mf">0.06</span><span class="p">,</span> <span class="n">right</span><span class="o">=</span><span class="mf">0.95</span><span class="p">,</span> <span class="n">top</span><span class="o">=</span><span class="mf">0.94</span><span class="p">,</span> <span class="n">wspace</span><span class="o">=</span><span class="mf">0.05</span><span class="p">)</span>
<span class="c1"># Make 4 subplots:</span>
<a href="../../api/image_api.html#matplotlib.image.AxesImage" title="matplotlib.image.AxesImage" class="sphx-glr-backref-module-matplotlib-image sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">im1</span></a> <span class="o">=</span> <a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">axs</span></a><span class="p">[</span><span class="mi">0</span><span class="p">,</span> <span class="mi">0</span><span class="p">]</span><span class="o">.</span><span class="n">imshow</span><span class="p">(</span><a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">Z</span></a><span class="p">,</span> <a href="../../api/_as_gen/matplotlib.colors.LinearSegmentedColormap.html#matplotlib.colors.LinearSegmentedColormap" title="matplotlib.colors.LinearSegmentedColormap" class="sphx-glr-backref-module-matplotlib-colors sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">cmap</span></a><span class="o">=</span><a href="../../api/_as_gen/matplotlib.colors.LinearSegmentedColormap.html#matplotlib.colors.LinearSegmentedColormap" title="matplotlib.colors.LinearSegmentedColormap" class="sphx-glr-backref-module-matplotlib-colors sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">blue_red1</span></a><span class="p">)</span>
<a href="../../api/_as_gen/matplotlib.figure.Figure.html#matplotlib.figure.Figure.colorbar" title="matplotlib.figure.Figure.colorbar" class="sphx-glr-backref-module-matplotlib-figure sphx-glr-backref-type-py-method"><span class="n">fig</span><span class="o">.</span><span class="n">colorbar</span></a><span class="p">(</span><a href="../../api/image_api.html#matplotlib.image.AxesImage" title="matplotlib.image.AxesImage" class="sphx-glr-backref-module-matplotlib-image sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">im1</span></a><span class="p">,</span> <span class="n">ax</span><span class="o">=</span><a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">axs</span></a><span class="p">[</span><span class="mi">0</span><span class="p">,</span> <span class="mi">0</span><span class="p">])</span>
<a href="../../api/_as_gen/matplotlib.colors.LinearSegmentedColormap.html#matplotlib.colors.LinearSegmentedColormap" title="matplotlib.colors.LinearSegmentedColormap" class="sphx-glr-backref-module-matplotlib-colors sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">cmap</span></a> <span class="o">=</span> <span class="n">plt</span><span class="o">.</span><span class="n">get_cmap</span><span class="p">(</span><span class="s1">'BlueRed2'</span><span class="p">)</span>
<a href="../../api/image_api.html#matplotlib.image.AxesImage" title="matplotlib.image.AxesImage" class="sphx-glr-backref-module-matplotlib-image sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">im2</span></a> <span class="o">=</span> <a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">axs</span></a><span class="p">[</span><span class="mi">1</span><span class="p">,</span> <span class="mi">0</span><span class="p">]</span><span class="o">.</span><span class="n">imshow</span><span class="p">(</span><a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">Z</span></a><span class="p">,</span> <a href="../../api/_as_gen/matplotlib.colors.LinearSegmentedColormap.html#matplotlib.colors.LinearSegmentedColormap" title="matplotlib.colors.LinearSegmentedColormap" class="sphx-glr-backref-module-matplotlib-colors sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">cmap</span></a><span class="o">=</span><a href="../../api/_as_gen/matplotlib.colors.LinearSegmentedColormap.html#matplotlib.colors.LinearSegmentedColormap" title="matplotlib.colors.LinearSegmentedColormap" class="sphx-glr-backref-module-matplotlib-colors sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">cmap</span></a><span class="p">)</span>
<a href="../../api/_as_gen/matplotlib.figure.Figure.html#matplotlib.figure.Figure.colorbar" title="matplotlib.figure.Figure.colorbar" class="sphx-glr-backref-module-matplotlib-figure sphx-glr-backref-type-py-method"><span class="n">fig</span><span class="o">.</span><span class="n">colorbar</span></a><span class="p">(</span><a href="../../api/image_api.html#matplotlib.image.AxesImage" title="matplotlib.image.AxesImage" class="sphx-glr-backref-module-matplotlib-image sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">im2</span></a><span class="p">,</span> <span class="n">ax</span><span class="o">=</span><a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">axs</span></a><span class="p">[</span><span class="mi">1</span><span class="p">,</span> <span class="mi">0</span><span class="p">])</span>
<span class="c1"># Now we will set the third cmap as the default. One would</span>
<span class="c1"># not normally do this in the middle of a script like this;</span>
<span class="c1"># it is done here just to illustrate the method.</span>
<a href="../../api/matplotlib_configuration_api.html#matplotlib.RcParams" title="matplotlib.RcParams" class="sphx-glr-backref-module-matplotlib sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">plt</span><span class="o">.</span><span class="n">rcParams</span></a><span class="p">[</span><span class="s1">'image.cmap'</span><span class="p">]</span> <span class="o">=</span> <span class="s1">'BlueRed3'</span>
<a href="../../api/image_api.html#matplotlib.image.AxesImage" title="matplotlib.image.AxesImage" class="sphx-glr-backref-module-matplotlib-image sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">im3</span></a> <span class="o">=</span> <a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">axs</span></a><span class="p">[</span><span class="mi">0</span><span class="p">,</span> <span class="mi">1</span><span class="p">]</span><span class="o">.</span><span class="n">imshow</span><span class="p">(</span><a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">Z</span></a><span class="p">)</span>
<a href="../../api/_as_gen/matplotlib.figure.Figure.html#matplotlib.figure.Figure.colorbar" title="matplotlib.figure.Figure.colorbar" class="sphx-glr-backref-module-matplotlib-figure sphx-glr-backref-type-py-method"><span class="n">fig</span><span class="o">.</span><span class="n">colorbar</span></a><span class="p">(</span><a href="../../api/image_api.html#matplotlib.image.AxesImage" title="matplotlib.image.AxesImage" class="sphx-glr-backref-module-matplotlib-image sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">im3</span></a><span class="p">,</span> <span class="n">ax</span><span class="o">=</span><a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">axs</span></a><span class="p">[</span><span class="mi">0</span><span class="p">,</span> <span class="mi">1</span><span class="p">])</span>
<a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">axs</span></a><span class="p">[</span><span class="mi">0</span><span class="p">,</span> <span class="mi">1</span><span class="p">]</span><span class="o">.</span><span class="n">set_title</span><span class="p">(</span><span class="s2">"Alpha = 1"</span><span class="p">)</span>
<span class="c1"># Or as yet another variation, we can replace the rcParams</span>
<span class="c1"># specification *before* the imshow with the following *after*</span>
<span class="c1"># imshow.</span>
<span class="c1"># This sets the new default *and* sets the colormap of the last</span>
<span class="c1"># image-like item plotted via pyplot, if any.</span>
<span class="c1">#</span>
<span class="c1"># Draw a line with low zorder so it will be behind the image.</span>
<a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">axs</span></a><span class="p">[</span><span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">]</span><span class="o">.</span><span class="n">plot</span><span class="p">([</span><span class="mi">0</span><span class="p">,</span> <span class="mi">10</span> <span class="o">*</span> <a href="https://docs.python.org/3/library/functions.html#float" title="builtins.float" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">np</span><span class="o">.</span><span class="n">pi</span></a><span class="p">],</span> <span class="p">[</span><span class="mi">0</span><span class="p">,</span> <span class="mi">20</span> <span class="o">*</span> <a href="https://docs.python.org/3/library/functions.html#float" title="builtins.float" class="sphx-glr-backref-module-builtins sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">np</span><span class="o">.</span><span class="n">pi</span></a><span class="p">],</span> <span class="n">color</span><span class="o">=</span><span class="s1">'c'</span><span class="p">,</span> <span class="n">lw</span><span class="o">=</span><span class="mi">20</span><span class="p">,</span> <span class="n">zorder</span><span class="o">=-</span><span class="mi">1</span><span class="p">)</span>
<a href="../../api/image_api.html#matplotlib.image.AxesImage" title="matplotlib.image.AxesImage" class="sphx-glr-backref-module-matplotlib-image sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">im4</span></a> <span class="o">=</span> <a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">axs</span></a><span class="p">[</span><span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">]</span><span class="o">.</span><span class="n">imshow</span><span class="p">(</span><a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">Z</span></a><span class="p">)</span>
<a href="../../api/_as_gen/matplotlib.figure.Figure.html#matplotlib.figure.Figure.colorbar" title="matplotlib.figure.Figure.colorbar" class="sphx-glr-backref-module-matplotlib-figure sphx-glr-backref-type-py-method"><span class="n">fig</span><span class="o">.</span><span class="n">colorbar</span></a><span class="p">(</span><a href="../../api/image_api.html#matplotlib.image.AxesImage" title="matplotlib.image.AxesImage" class="sphx-glr-backref-module-matplotlib-image sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">im4</span></a><span class="p">,</span> <span class="n">ax</span><span class="o">=</span><a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">axs</span></a><span class="p">[</span><span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">])</span>
<span class="c1"># Here it is: changing the colormap for the current image and its</span>
<span class="c1"># colorbar after they have been plotted.</span>
<a href="../../api/cm_api.html#matplotlib.cm.ScalarMappable.set_cmap" title="matplotlib.cm.ScalarMappable.set_cmap" class="sphx-glr-backref-module-matplotlib-cm sphx-glr-backref-type-py-method"><span class="n">im4</span><span class="o">.</span><span class="n">set_cmap</span></a><span class="p">(</span><span class="s1">'BlueRedAlpha'</span><span class="p">)</span>
<a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray" title="numpy.ndarray" class="sphx-glr-backref-module-numpy sphx-glr-backref-type-py-class sphx-glr-backref-instance"><span class="n">axs</span></a><span class="p">[</span><span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">]</span><span class="o">.</span><span class="n">set_title</span><span class="p">(</span><span class="s2">"Varying alpha"</span><span class="p">)</span>
<span class="c1">#</span>
<a href="../../api/_as_gen/matplotlib.figure.Figure.html#matplotlib.figure.Figure.suptitle" title="matplotlib.figure.Figure.suptitle" class="sphx-glr-backref-module-matplotlib-figure sphx-glr-backref-type-py-method"><span class="n">fig</span><span class="o">.</span><span class="n">suptitle</span></a><span class="p">(</span><span class="s1">'Custom Blue-Red colormaps'</span><span class="p">,</span> <span class="n">fontsize</span><span class="o">=</span><span class="mi">16</span><span class="p">)</span>
<a href="../../api/_as_gen/matplotlib.figure.Figure.html#matplotlib.figure.Figure.subplots_adjust" title="matplotlib.figure.Figure.subplots_adjust" class="sphx-glr-backref-module-matplotlib-figure sphx-glr-backref-type-py-method"><span class="n">fig</span><span class="o">.</span><span class="n">subplots_adjust</span></a><span class="p">(</span><span class="n">top</span><span class="o">=</span><span class="mf">0.9</span><span class="p">)</span>
<a href="../../api/_as_gen/matplotlib.pyplot.show.html#matplotlib.pyplot.show" title="matplotlib.pyplot.show" class="sphx-glr-backref-module-matplotlib-pyplot sphx-glr-backref-type-py-function"><span class="n">plt</span><span class="o">.</span><span class="n">show</span></a><span class="p">()</span>
</pre></div>
</div>
<img alt="Custom Blue-Red colormaps, Alpha = 1, Varying alpha" class="sphx-glr-single-img" src="../../_images/sphx_glr_custom_cmap_002.png" />
<hr class="docutils" />
<div class="section" id="references">
<h3>References<a class="headerlink" href="#references" title="Permalink to this headline">¶</a></h3>
<p>The use of the following functions, methods, classes and modules is shown
in this example:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">matplotlib</span>
<a href="../../api/_as_gen/matplotlib.axes.Axes.imshow.html#matplotlib.axes.Axes.imshow" title="matplotlib.axes.Axes.imshow" class="sphx-glr-backref-module-matplotlib-axes-Axes sphx-glr-backref-type-py-method"><span class="n">matplotlib</span><span class="o">.</span><span class="n">axes</span><span class="o">.</span><span class="n">Axes</span><span class="o">.</span><span class="n">imshow</span></a>
<a href="../../api/_as_gen/matplotlib.pyplot.imshow.html#matplotlib.pyplot.imshow" title="matplotlib.pyplot.imshow" class="sphx-glr-backref-module-matplotlib-pyplot sphx-glr-backref-type-py-function"><span class="n">matplotlib</span><span class="o">.</span><span class="n">pyplot</span><span class="o">.</span><span class="n">imshow</span></a>
<a href="../../api/_as_gen/matplotlib.figure.Figure.html#matplotlib.figure.Figure.colorbar" title="matplotlib.figure.Figure.colorbar" class="sphx-glr-backref-module-matplotlib-figure-Figure sphx-glr-backref-type-py-method"><span class="n">matplotlib</span><span class="o">.</span><span class="n">figure</span><span class="o">.</span><span class="n">Figure</span><span class="o">.</span><span class="n">colorbar</span></a>
<a href="../../api/_as_gen/matplotlib.pyplot.colorbar.html#matplotlib.pyplot.colorbar" title="matplotlib.pyplot.colorbar" class="sphx-glr-backref-module-matplotlib-pyplot sphx-glr-backref-type-py-function"><span class="n">matplotlib</span><span class="o">.</span><span class="n">pyplot</span><span class="o">.</span><span class="n">colorbar</span></a>
<a href="../../api/colors_api.html#module-matplotlib.colors" title="matplotlib.colors" class="sphx-glr-backref-module-matplotlib sphx-glr-backref-type-py-module"><span class="n">matplotlib</span><span class="o">.</span><span class="n">colors</span></a>
<a href="../../api/_as_gen/matplotlib.colors.LinearSegmentedColormap.html#matplotlib.colors.LinearSegmentedColormap" title="matplotlib.colors.LinearSegmentedColormap" class="sphx-glr-backref-module-matplotlib-colors sphx-glr-backref-type-py-class"><span class="n">matplotlib</span><span class="o">.</span><span class="n">colors</span><span class="o">.</span><span class="n">LinearSegmentedColormap</span></a>
<a href="../../api/_as_gen/matplotlib.colors.LinearSegmentedColormap.html#matplotlib.colors.LinearSegmentedColormap.from_list" title="matplotlib.colors.LinearSegmentedColormap.from_list" class="sphx-glr-backref-module-matplotlib-colors-LinearSegmentedColormap sphx-glr-backref-type-py-method"><span class="n">matplotlib</span><span class="o">.</span><span class="n">colors</span><span class="o">.</span><span class="n">LinearSegmentedColormap</span><span class="o">.</span><span class="n">from_list</span></a>
<a href="../../api/cm_api.html#module-matplotlib.cm" title="matplotlib.cm" class="sphx-glr-backref-module-matplotlib sphx-glr-backref-type-py-module"><span class="n">matplotlib</span><span class="o">.</span><span class="n">cm</span></a>
<a href="../../api/cm_api.html#matplotlib.cm.ScalarMappable.set_cmap" title="matplotlib.cm.ScalarMappable.set_cmap" class="sphx-glr-backref-module-matplotlib-cm-ScalarMappable sphx-glr-backref-type-py-method"><span class="n">matplotlib</span><span class="o">.</span><span class="n">cm</span><span class="o">.</span><span class="n">ScalarMappable</span><span class="o">.</span><span class="n">set_cmap</span></a>
<span class="n">matplotlib</span><span class="o">.</span><span class="n">pyplot</span><span class="o">.</span><span class="n">register_cmap</span>
<a href="../../api/cm_api.html#matplotlib.cm.register_cmap" title="matplotlib.cm.register_cmap" class="sphx-glr-backref-module-matplotlib-cm sphx-glr-backref-type-py-function"><span class="n">matplotlib</span><span class="o">.</span><span class="n">cm</span><span class="o">.</span><span class="n">register_cmap</span></a>
</pre></div>
</div>
<p class="sphx-glr-script-out">Out:</p>
<div class="sphx-glr-script-out highlight-none notranslate"><div class="highlight"><pre><span></span><function register_cmap at 0x7fedff1a1ee0>
</pre></div>
</div>
<p class="sphx-glr-timing"><strong>Total running time of the script:</strong> ( 0 minutes 1.707 seconds)</p>
<div class="sphx-glr-footer class sphx-glr-footer-example docutils container" id="sphx-glr-download-gallery-color-custom-cmap-py">
<div class="sphx-glr-download sphx-glr-download-python docutils container">
<a class="reference download internal" download="" href="../../_downloads/fba15be770735fdb1b9272eaaf80104e/custom_cmap.py"><code class="xref download docutils literal notranslate"><span class="pre">Download</span> <span class="pre">Python</span> <span class="pre">source</span> <span class="pre">code:</span> <span class="pre">custom_cmap.py</span></code></a></div>
<div class="sphx-glr-download sphx-glr-download-jupyter docutils container">
<a class="reference download internal" download="" href="../../_downloads/26f5b5c2451ffd373350d617a08d2e7d/custom_cmap.ipynb"><code class="xref download docutils literal notranslate"><span class="pre">Download</span> <span class="pre">Jupyter</span> <span class="pre">notebook:</span> <span class="pre">custom_cmap.ipynb</span></code></a></div>
</div>
<p class="sphx-glr-signature">Keywords: matplotlib code example, codex, python plot, pyplot
<a class="reference external" href="https://sphinx-gallery.readthedocs.io">Gallery generated by Sphinx-Gallery</a></p>
</div>
</div>
</div>
</div>
</div>
</div>
<div class="clearer"></div>
</div>
<footer>
<div class="footer">
© Copyright 2002 - 2012 John Hunter, Darren Dale, Eric Firing, Michael Droettboom and the Matplotlib development team; 2012 - 2020 The Matplotlib development team.
<br />
Last updated on Aug 14, 2020.
Created using
<a href="http://sphinx-doc.org/">Sphinx</a> 3.1.1.
Doc version v3.3.1-2-ge49322daa.
</div>
</footer>
</body>
</html>