In [1]:

    

import this


    

    




The Zen of Python, by Tim Peters

Beautiful is better than ugly.
Explicit is better than implicit.
Simple is better than complex.
Complex is better than complicated.
Flat is better than nested.
Sparse is better than dense.
Readability counts.
Special cases aren't special enough to break the rules.
Although practicality beats purity.
Errors should never pass silently.
Unless explicitly silenced.
In the face of ambiguity, refuse the temptation to guess.
There should be one-- and preferably only one --obvious way to do it.
Although that way may not be obvious at first unless you're Dutch.
Now is better than never.
Although never is often better than *right* now.
If the implementation is hard to explain, it's a bad idea.
If the implementation is easy to explain, it may be a good idea.
Namespaces are one honking great idea -- let's do more of those!

In [2]:

    

import antigravity


    

In [3]:

    

foo = [1, 2, 3]
for i in foo: 
    if i == 0: 
        break 

else: print("i was never 0")


    

    




i was never 0

In [4]:

    

x = 1.4e-3
x


    

    
Out[4]:





0.0014

In [5]:

    

x = 5
1 < x < 10


    

    
Out[5]:





True

In [6]:

    

def draw_point(x, y):
    print x, y

point_foo = (3, 4)
point_bar = {'y': 3, 'x': 2}

draw_point(*point_foo)
draw_point(**point_bar)


    

    




3 4
2 3

In [7]:

    

a = ['a', 'b', 'c', 'd', 'e']
for index, item in enumerate(a): print index, item


    

    




0 a
1 b
2 c
3 d
4 e

In [16]:

    

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

def bar(n):
    '''
    return the even number
    '''
    if n%2 == 0:
        return n
    
x = (n for n in foo if bar(n))
for n in x:
    print n


    

    




2
4
6
8

In [17]:

    

#The advantage of this is that you don't need intermediate storage, which you would need if you did
x = [n for n in foo if bar(n)]


    

In [18]:

    

#You can append many if statements to the end of the generator, basically replicating nested for loops:
n = ((a,b) for a in range(0,2) for b in range(4,6))
for i in n:
    print i


    

    




(0, 4)
(0, 5)
(1, 4)
(1, 5)

In [19]:

    

from __future__ import braces


    

    




  File "<ipython-input-19-2aebb3fc8ecf>", line 1
    from __future__ import braces
SyntaxError: not a chance

In [26]:

    

def foo(x=[]):
    x.append(1)
    print x


    

In [27]:

    

foo()
foo()
foo()


    

    




[1]
[1, 1]
[1, 1, 1]

In [28]:

    

def foo(x=None):
    if x is None:
        x = []
    x.append(1)
    print x


    

In [29]:

    

foo()
foo()
foo()


    

    




[1]
[1]
[1]

In [10]:

    

import matplotlib.pyplot as plt
import random

#this dict will save the key your pressed
pressed_key = {}

def press(event):
    print('press', event.key)
    if event.key=='q':
        #close the current figure
        plt.close(event.canvas.figure)
        pressed_key['key'] = event.key

for i in range(10):
    #generate x, y for plotting
    x = random.sample(range(1, 100), 20)
    y = random.sample(range(1, 100), 20)
    
    fig = plt.figure()
    plt.plot(x,y,'o')
    
    fig.canvas.mpl_connect('key_press_event', press)
        
    plt.show() 
        
    #if the pressed key is q, then stop looping through figures
    #note, here must use dict.get('key'), otherwise will have key error
    if pressed_key.get('key') == 'q':
        break


    

    




('press', 'q')

In [2]:

    

a = [1,2,3,4,5,6,7,8,9,10]
print a[::2]
print a[::-2]


    

    




[1, 3, 5, 7, 9]
[10, 8, 6, 4, 2]

In [3]:

    

a = 10
b = 5
print a, b


    

    




10 5

In [4]:

    

a, b = b, a
print a, b


    

    




5 10

In [2]:

    

sum_dict = {}
value = 1
sum_dict[value] = sum_dict.get(value, 0) + 1


    

In [3]:

    

sum_dict


    

    
Out[3]:





{1: 1}

In [5]:

    

y = 1
x = 3 if (y==1) else 2
x


    

    
Out[5]:





3

In [6]:

    

x = 3 if (y == 1) else 2 if (y == -1) else 1
x


    

    
Out[6]:





3

In [ ]:

    

#Note that you can use if ... else in any expression. For example:
(func1 if y == 1 else func2)(arg1, arg2) 

#or 
x = (class1 if y == 1 else class2)(arg1, arg2)


    

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