In [1]:

    

# This is a comment in Python

print("Hello World!")


    

    




Hello World!

In [2]:

    

2 + 2


    

    
Out[2]:





4

In [3]:

    

x = 5


    

In [4]:

    

x / 2


    

    
Out[4]:





2.5

In [5]:

    

x // 2


    

    
Out[5]:





2

In [6]:

    

2 ** 10


    

    
Out[6]:





1024

In [7]:

    

2 ** 10000


    

    
Out[7]:





19950631168807583848837421626835850838234968318861924548520089498529438830221946631919961684036194597899331129423209124271556491349413781117593785932096323957855730046793794526765246551266059895520550086918193311542508608460618104685509074866089624888090489894838009253941633257850621568309473902556912388065225096643874441046759871626985453222868538161694315775629640762836880760732228535091641476183956381458969463899410840960536267821064621427333394036525565649530603142680234969400335934316651459297773279665775606172582031407994198179607378245683762280037302885487251900834464581454650557929601414833921615734588139257095379769119277800826957735674444123062018757836325502728323789270710373802866393031428133241401624195671690574061419654342324638801248856147305207431992259611796250130992860241708340807605932320161268492288496255841312844061536738951487114256315111089745514203313820202931640957596464756010405845841566072044962867016515061920631004186422275908670900574606417856951911456055068251250406007519842261898059237118054444788072906395242548339221982707404473162376760846613033778706039803413197133493654622700563169937455508241780972810983291314403571877524768509857276937926433221599399876886660808368837838027643282775172273657572744784112294389733810861607423253291974813120197604178281965697475898164531258434135959862784130128185406283476649088690521047580882615823961985770122407044330583075869039319604603404973156583208672105913300903752823415539745394397715257455290510212310947321610753474825740775273986348298498340756937955646638621874569499279016572103701364433135817214311791398222983845847334440270964182851005072927748364550578634501100852987812389473928699540834346158807043959118985815145779177143619698728131459483783202081474982171858011389071228250905826817436220577475921417653715687725614904582904992461028630081535583308130101987675856234343538955409175623400844887526162643568648833519463720377293240094456246923254350400678027273837755376406726898636241037491410966718557050759098100246789880178271925953381282421954028302759408448955014676668389697996886241636313376393903373455801407636741877711055384225739499110186468219696581651485130494222369947714763069155468217682876200362777257723781365331611196811280792669481887201298643660768551639860534602297871557517947385246369446923087894265948217008051120322365496288169035739121368338393591756418733850510970271613915439590991598154654417336311656936031122249937969999226781732358023111862644575299135758175008199839236284615249881088960232244362173771618086357015468484058622329792853875623486556440536962622018963571028812361567512543338303270029097668650568557157505516727518899194129711337690149916181315171544007728650573189557450920330185304847113818315407324053319038462084036421763703911550639789000742853672196280903477974533320468368795868580237952218629120080742819551317948157624448298518461509704888027274721574688131594750409732115080498190455803416826949787141316063210686391511681774304792596709376

In [8]:

    

len(str(2 ** 100000))


    

    
Out[8]:





30103

In [9]:

    

s = "python"


    

In [10]:

    

s + s


    

    
Out[10]:





'pythonpython'

In [11]:

    

s * 3


    

    
Out[11]:





'pythonpythonpython'

In [12]:

    

s = input() # type infoclock


    

    




infoclock

In [13]:

    

s[0]


    

    
Out[13]:





'i'

In [14]:

    

s[1]


    

    
Out[14]:





'n'

In [15]:

    

s[-1]


    

    
Out[15]:





'k'

In [16]:

    

s[-2]


    

    
Out[16]:





'c'

In [17]:

    

s[1:]


    

    
Out[17]:





'nfoclock'

In [18]:

    

s[:1]


    

    
Out[18]:





'i'

In [19]:

    

s[2:]


    

    
Out[19]:





'foclock'

In [20]:

    

s[:2]


    

    
Out[20]:





'in'

In [21]:

    

s[:-1]


    

    
Out[21]:





'infocloc'

In [22]:

    

s[:-2]


    

    
Out[22]:





'infoclo'

In [23]:

    

s[2 : -2]


    

    
Out[23]:





'foclo'

In [24]:

    

s[2 : -2 : 2]


    

    
Out[24]:





'fco'

In [25]:

    

l = [2, 3, 5, 7, 11]


    

In [26]:

    

l[0] * l[-1]


    

    
Out[26]:





22

In [27]:

    

l.append(13)
print(l)


    

    




[2, 3, 5, 7, 11, 13]

In [28]:

    

l2 = [2, 4, 6, 8]
l + l2


    

    
Out[28]:





[2, 3, 5, 7, 11, 13, 2, 4, 6, 8]

In [29]:

    

v = [0] * 10
print(v)


    

    




[0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

In [30]:

    

v = [1] * 10
v[0] = 33
print(v)


    

    




[33, 1, 1, 1, 1, 1, 1, 1, 1, 1]

In [31]:

    

# s[0] = 'x' # this will fail


    

In [32]:

    

s = "python is awesome"
v = s.split()
print(v)


    

    




['python', 'is', 'awesome']

In [33]:

    

v.append(100)
print(v)


    

    




['python', 'is', 'awesome', 100]

In [34]:

    

d = {}
d['a'] = 'alex'
d['f'] = 'fmi'
d[3] = 42
print(d)


    

    




{3: 42, 'f': 'fmi', 'a': 'alex'}

In [35]:

    

for key in d:
    print ('Key: {0}; Value: {1}'.format(key, d[key]))


    

    




Key: 3; Value: 42
Key: f; Value: fmi
Key: a; Value: alex

In [36]:

    

d[3] += 1
print(d[3])


    

    




43

In [37]:

    

for x in range(5):
    print("I want " + str(x + 1) + " apples.")


    

    




I want 1 apples.
I want 2 apples.
I want 3 apples.
I want 4 apples.
I want 5 apples.

In [38]:

    

this_is_true = True
if this_is_true:
    print("the answer to life, the universe and everything is 42")
else:
    whatever # change this_is_true to False


    

    




the answer to life, the universe and everything is 42

In [39]:

    

x = 0
while x <= 5:
    x += 1
    
    if x == 1:
        continue

    print("I am number", x)
    
    if x == 4:
        break


    

    




I am number 2
I am number 3
I am number 4

In [40]:

    

v = [2, 3, 5, 7, 11]
doubles = [x*2 for x in v]
print(doubles)


    

    




[4, 6, 10, 14, 22]

In [41]:

    

[x*x for x in range(30) if x % 2 == 1]


    

    
Out[41]:





[1, 9, 25, 49, 81, 121, 169, 225, 289, 361, 441, 529, 625, 729, 841]

In [42]:

    

N = 10
[0] * N


    

    
Out[42]:





[0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

In [43]:

    

[[0]*N for i in range(N)]


    

    
Out[43]:





[[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
 [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
 [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
 [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
 [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
 [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
 [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
 [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
 [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
 [0, 0, 0, 0, 0, 0, 0, 0, 0, 0]]

In [44]:

    

# Syntax for importing
from random import randint

v = [randint(1, 100) for i in range(10)]
print(v)


    

    




[25, 63, 96, 81, 90, 39, 23, 54, 8, 86]

In [45]:

    

v.sort()
print(v)


    

    




[8, 23, 25, 39, 54, 63, 81, 86, 90, 96]

In [46]:

    

line = "1 3 7 13 2\n"
line.strip()


    

    
Out[46]:





'1 3 7 13 2'

In [47]:

    

line.strip().split()


    

    
Out[47]:





['1', '3', '7', '13', '2']

In [48]:

    

[int(x) for x in line.strip().split()]


    

    
Out[48]:





[1, 3, 7, 13, 2]

In [49]:

    

sorted([int(x) for x in line.strip().split()])


    

    
Out[49]:





[1, 2, 3, 7, 13]

In [50]:

    

[alfa, beta, gamma, epsilon, omega] = sorted([int(x) for x in line.strip().split()])
print(alfa, omega)


    

    




1 13

In [51]:

    

beta, epsilon = epsilon, beta
print(beta)


    

    




7

In [52]:

    

# How to count number of appearances
from collections import defaultdict

v = [randint(1, 10) for i in range(100)]
d = defaultdict(int)

for x in v:
    d[x] += 1

for key in d:
    print(key, d[key])


    

    




1 8
2 10
3 10
4 12
5 8
6 7
7 8
8 10
9 10
10 17

In [53]:

    

v = 'ABCD'

from itertools import permutations

for p in permutations(v):
    print(" ".join(p))


    

    




A B C D
A B D C
A C B D
A C D B
A D B C
A D C B
B A C D
B A D C
B C A D
B C D A
B D A C
B D C A
C A B D
C A D B
C B A D
C B D A
C D A B
C D B A
D A B C
D A C B
D B A C
D B C A
D C A B
D C B A

In [54]:

    

from itertools import combinations
for c in combinations(v, 2):
    print(" ".join(c))


    

    




A B
A C
A D
B C
B D
C D

In [55]:

    

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!