A quick cheat sheet on Python

This is not a complete python 3 tutorial. This just quick note to remember the python 3 syntax.

Python Data Type:

String

Here is the example of String indexing and slicing:

>>> string= "onetwothree"
>>> string[1]
'n'
>>> string[1:]
'netwothree'
>>> string[2:]
'etwothree'
>>> string[2:5]
'etw'
>>> string[2:5:7] # Start:Stop:Step Size
'e'
>>> 

​

Format String

>>> print("This is {}".format(string))
This is one two three

>>> print("This is {1}".format(string))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
IndexError: Replacement index 1 out of range for positional args tuple

>>> print("This is {0}".format(string))
This is one two three

>>> print("This is {0}".format(string,string))
This is one two three

>>> print("This is {0} {1}".format(string,string))
This is one two three one two three

>>> print("This is {0} {1}".format(a='One',b='Two'))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
IndexError: Replacement index 0 out of range for positional args tuple

>>> print("This is {a} {b}".format(a='One',b='Two')) #Assign Variable for the Format
This is One Two

>>> string.split() #Convert a string to List
['one', 'two', 'three']

>>> print(f'hmmm {test}')
hmmm testing
>>> 
>>> print(f"Here it is %s"%(string))
Here it is TEST
>>> print(f"Here it is %s" %(string))
Here it is TEST
>>> print(f"Here it is {string}")
Here it is TEST

>>> 

Variables

Assign data types a variable to reference later. Variable name cant contain special charcters except _

var1 = "String" #String 

var2 = 1337 # Integer

var3 = True # Boolean

var4 = 1337.1 #Float

var5 = ["Cyber","World", 1337]

var6 = {"key1":"value1","key2":"value2"} #Dictionaries

var7 = {"Test1","Test2"} #Sets

var8 = (1,"Cyber") #Tuples

Python Operators

Conditional

if (1==1) or (2=1):
    print("Condition is True")

elif (2==2) and (3==3):
    print("Condition is True")

else:
    print("Nothing match?")

Lists

• Lists are ordered Sequence

• It supports indexing and slicing

  lists = [“Cyber”,1337]

  lists = [“Cyber”,1337] lists [‘Cyber’, 1337] lists[0] ‘Cyber’ lists[:1] [‘Cyber’] lists[1:] [1337]

  li = [1,2,3] lists+li [‘Cyber’, 1337, 1, 2, 3]

  lists[0] = ‘Cyber World’ lists [‘Cyber World’, 1337]

  lists[0].upper() ‘CYBER WORLD’

Nested List:

>>> lists
['Cyber World', 1337]

>>> listing = [1,2]

>>> lists.append(listing)

>>> lists
['Cyber World', 1337, [1, 2]]

>>> lists[2]
[1, 2]

>>> lists[2][0]
1

Useful Available method:
list.append(x): Add an item to the end
list.insert(i,x): insert an item to given postion.
list.remove(x): Remove the first item from the list whose value is equal to x
list.clear(): Remove all items from the list.
list.reverse(): Reverse the elements of the list in place.

Dictionaries

It is key and value pair. Use dictionary when need to retrive value by key name.

dicto = {'key':'val1','key1':'val2'}
print(dicto['key1'])

Tuples

Tuples is immutable, mean, we can’t change or modify Tuples

>>> tupl = (1,2,3)
>>> tupl[0]
1

Loop

For Loop

Looping through list:

list1 = [1,2,3]
for n in list1:
    if n==2:
        print("Loop rach the"+str(n))
    else:
        print('Wtf')

listing = 0

for n in list1:
    listing += listing+n

print(listing)

Looping through a string:

strange = "This is strange"

for s in strange:
    print(s)

Looping through the Dictionary:

d = {'key1':1,'key2':2}
for key,value in d.items():
    print(key)
    print(value)

While Loop

Loop until y=False

>>> y = True
>>> while y:
...     print(x)
...     if x == 10:
...             y=False #Or break statement
...     x += 1
... 
0
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More to update!!!