# coding:utf-8

import matplotlib.pyplot as pl

from matplotlib.ticker import MultipleLocator, FuncFormatter

import numpy as np

def pi_formatter(x, pos):

'''

:param x:

:param pos:

:return:

'''

m = np.round(x / (np.pi/4))

n = 4

while m!=0 and m%2==0: m, n = m//2, n//2

if m == 0:

return "0"

if m == 1 and n == 1:

return "$\pi$"

if n == 1:

return r"$%d \pi$" %m

if m == 1:

return r"$\frac{\pi}{%d}$" %n

return r"$\frac{%d \pi}{%d}$" %(m,n)

def main():

x = np.arange(0, 4*np.pi, 0.01)

y = np.sin(x)

pl.figure(figsize = (8, 4))

pl.plot(x, y)

ax = pl.gca()

pl.ylim(-1.5, 1.5)

pl.xlim(0, np.max(x))

pl.subplots_adjust(bottom = 0.15)

# 开启网格

pl.grid()

# 主刻度为pi/4

ax.xaxis.set_major_locator(MultipleLocator(np.pi/4))

# 主刻度文本,传入回调函数

ax.xaxis.set_major_formatter(FuncFormatter(pi_formatter))

# 副刻度pi/20

ax.xaxis.set_minor_locator(MultipleLocator(np.pi/20))

# 设置刻度文本大小

for tick in ax.xaxis.get_major_ticks():

tick.label1.set_fontsize(16)

pl.show()

if __name__ == '__main__':

main()