Basic calculations

Exponentiation

2 ** 4 #out 16

Modulo: (Rest of the division)

5 % 2 #out 1

Variable definition

var=5
super_crazy_var=5

Comment:

# Some comment

String

String definition (In quotes):

"I can't touch anything"

Print variable:

print(var)

Format method:

print('My number is {} and my name is {}'.format(2,"Jan"))

Format method 2:

print('My number is {num} and my name is {name} and {num}'.format(num=2,name="Jan"))

Indexing of strings:

pintf(s[0])

Slicing: (From 0 to 4)

s="Hello world!"
s[:4] #out 'Hell'

Data types

Booleans:

True, False

List:

list = ['a', 'b', 'c']

List append:

list.append('d')

Change value in list:

list[0]="new value"

Neasted list:

list = [1,2,[1,2,["double_nested"]]]
print(list[3][2]) #output ["double_neasted"]
print(list[3][2][0]) #output "double_neasted"

Dictionary:

dic = {"key1":"value", "key2":1}

Neasted Dictionary:

dic = {"k1":{"inner_key":[1,2]}}

Touple(Immutable):

touple = (1,2,3)
print(t[0]) #out 1

Difference between tuple and list:

  • List - Mutable
  • Touple - Immutable

Set(collection of unique elements):

set={1,1,1,2,2,2,3} #out {1,2,3}

Array to Set conversion:

set([1,1,1,2,2,2,2,3,3]) #out {1,2,3}

Add to set:

set={1,1,1,2,2,2,3} #out {1,2,3}
set.add(5)
print(set) #out {1,2,3,5}

Comparators

Equal:

1 == 2 #False

And:

(1 < 2 )and (2 > 3) #False

Or:

(1 < 2) or (2 > 1) #True

If

if 1 < 2:
    print('True')

If,elsif,else:

if 1 == 2:
    print('Never')
elif 3 == 3:
    print('True')
else:
    print('else')

Loops

For:

seq = [1,2,3,4,5]
for num in seq:
    print('Num: ' + str(num))

While:

i = 1
while i < 5:
    print('i is: {}'.format(i))
    i+=1

Range:

range(0, 5)
for x in range(0, 5):
    print(x) # 0-5

List, range:

list(range(10))

List comprehension:

[num**2 for num in range(5)] #out [0, 1, 4, 9, 16]

Functions

Function:

def my_func(param1):
    print(param1)
my_func('Hello world!')
my_func #out <function my_func at 0x7f81432c9b90> #what is the object

Default function parameter value:

def my_func(name='Default'):
    print('Hello ' + name)
my_func() #out Hello Default

Function return:

def square(num):
    return num**2

Documentation string:

def square(num):
"""
This is documentation
Multiple lines
"""
    return num**2

Collection methods

Map function: Apply function to each element of seq

def times2(var):
    return var*2

list(map(times2, list(range(4)))) #out [0, 2, 4, 6]

Lambda expressions:

times2 = lambda var:var*2

list(map(times2, list(range(4)))) #out [0, 2, 4, 6]

Pass lambda as param:

list(map(lambda num: num*3, list(range(4)))) #out [0, 3, 6, 9]

Filter:

list(filter(lambda num: num%2 == 0, range(4))) #out [0, 2]

String methods:

s = 'Some string value'
s.lower() # lowercase
s.upper() # uppercase
s.split() # split by whitespace
s.split('#pattern') # split by #pattern

Dictionary methods:

d = {'k1': 1, 'k2': 2}
d.keys() #out dict_keys(['k1', 'k2'])
d.items() #out dict_items([('k1', 1), ('k2', 2)])
d.values() #out dict_values([1, 2])

List methods:

list = [0,1,2,3,4]
list.pop() #return and remove last element, out 4
list.pop(0) #return and remove element of index 0, out 0
list.append("value") #out [1, 2, 3, 'value']

In operator:

'x' in [1, 2, 3] #out False
'x' in ['x', 'y', 'z'] #out True

Touple unpacking:

x = [(1,2),(3,4),(5,6)]
for (a,b) in x:
    print(b) #out 2, 4, 6

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