# python types

3/4

3.0/4.0

print("Hello " + "Ista")

# assignment

x = 3

y = 4

z = x + y

print(z)

## factorial

f8 = 8*7*6*5*4*3*2

## divisible by exercise (note that these would be treated as integers in python 2)

x = 123456789

y = [3607, 3803, 4013]

x / y[0]

x / y[1]

x / y[2]

x % y[0] == 0

x % y[1] == 0

x % y[2] == 0

## floats vs integers

## works

x ** 1000

## too big

(1.0 * x)**1000

## type conversion

xs = str(x)

xi = int(x)

xf = float(x)

type(xs)

type(xi)

type(xf)

## methods

xs.find("3")

xs.count("3")

## logic

1 < 5 < 4

(1 < 5) | (5 < 4)

## branching

if (x < 5):

print(x) # can i put comments here?

else: # can i put comments here?

print("x not less than 5") # can i put comments here?

# another way to use if:

z = "hello" if (x > 5) else "Good bye"

print(z)

## lists

x = [1, 2, 3, 4, 5, 6, 7, 8, 9]

s = [] # empty list

s.append(1)

# lists can hold many things:

s.append("a")

s.append(s)

s.append([1, 2, 3])

"a" in s

1 in s

[1,2,3] in s

s.remove(s)

## delete by position

del s[2]

## append multiple elements

s.extend(["a", "b", "c"])

## insert

s.insert(0, s)

## indexing

s[4:7]

# if the first index is zero you can use the shortcut:

s[:4] # first four elements

s[-3:] # last three elements

len(xs)

len(s)

## dictionaries

s = {} # empty dictionary

s['bob'] = 1

s['alice'] = 1

s["ken"] = 2

s = {'bob': 1, 'alice': 2, 'ken': 3}

## index dictionaries

s['bob']

## tuples (unchangeable)

t = (1, 2)

## sets

myset = set([1, 2, 3])

myset == {1, 2, 3}

## functions

def f(x):

return(x * x)

f(4)

## functions

def f(x, y):

return(x * y)

f(3, 4)

def h(x):

return(x*x)

def f(x,y,z):

return(z(x) + z(y))

f(1, 2, h)

# default arguments

f(1, 2)

def f(x,y,z=h):

return(z(x) + z(y))

f(1, 2)

def f(x=xi,y=xi,z=h):

return(z(x) + z(y))

f(z = h, x = 1, y = 2)

## package (*module*) management

import numpy ## import all numpy functions with numpy namespace

import math as m ## import math with m namespace

from math import * ## import all functions from math

## user writen files can be imported in the same way. The default namespace is the name of the file.

## for loops

names = ["alice", "robert", "jillian", "sue", "margret", "bobby"]

for name in names:

print(name)

for i in range(0, len(names)):

print(i)

## note that python2 has both range and xrange, python2 just has range, which mostly works like python2 xrange

[print(n) for n in names]

import urllib

import urllib.request

g = urllib.request.urlopen("http://google.com")