My Python Register

Noting down my flow with Python

Help about a module

help('modules') # This lists all built-in modules
module.__doc__ # To see some documentation about a specific module

To Check BuiltIn Functions in a module

import hashlib # Need to import the module first
dir(hashlib)

Importing Modules

#  greet.py
def msg():
 return 'Hey Wassup'

# welcome.py
import greet
 greet.msg()

import greet as g # Can be aliased
 g.msg() 

# A module can be stand-alone runnable script.
if __name__ == '__main__':
 from greet import msg # specific functions can also be imported
 msg()

Strings

str_hello='hello_World'
print(str_hello[0:5])

print type(str_hello) # To check the dataType

print ''.join(reversed(str_hello)) # To reverse a string easily

Ways to Concatenate string and int

Output : list12

I. Using str() fn.

x = 'list'
y = 12

print x+str(y)

II. Using % Operator

print "%s%s"%(x,y)

III. Using format function

print "{}{}".format(x,y)

Sets, FrozenSets and MultiSets

set1 = {1,2,3,1,2,5,2,8,}
print set1

set2 = set('hello')
set2.add('y') #Can add new elements easily
print set2

set3 = frozenset('lulzsec') #Cannot add new elements
print 'l' in set3 # Testing if element is present in a set, returns 'bool'
print 's' not in set3 # just opposite of 'in'
print "No. of Elements in FrozenSet_set3 ==> {}".format(len(set3))

set([8, 1, 2, 3, 5])
set(['y', 'h', 'e', 'l', 'o'])
True
False
No. of Elements in FrozenSet_set3 ==> 6

set4 = {10,20,30,40,50}
set5 = {30,40,50,60}

## Operations

### intersection (&)
print set4.intersection(set5)
print set4 & set5

### union (|)
print set4.union(set5)
print set4 | set5

### difference (-)
print set4.difference(set5)
print set4 - set5

### symmetric_difference (&)
print set4.symmetric_difference(set5)
print set4 ^ set5

### issubset (<=)
print set4.issubset(set5)
print set4 <= set5

### issuperset (>=)
print set4.issuperset(set5)
print set4 >= set5

### isdisjoint
print set4.isdisjoint(set5)

set([40, 50, 30])
set([40, 10, 50, 20, 60, 30])
set([10, 20])
set([10, 20, 60])
False
False
False

set6 = set4 | set5
set6.add(60)
set6.add(70)
print set6
print len(set6) # duplicates not allowed in sets

set([70, 40, 10, 50, 20, 60, 30])
7

# multisets.py

from collections import Counter
multisetCounter = Counter(['a','a','b'])
print multisetCounter

#OR Using multiset.py from pypi.org
import multiset
s1 = multiset.Multiset('aab')
print s1

Counter({'a': 2, 'b': 1})
{a, a, b}

Complex Numbers and other data types

comp_num1 = 3 + 13j
print comp_num1
print(type(comp_num1))
comp_num2 = complex(2,5)
print comp_num2

print "Real Part (comp_num2) :: {}".format(comp_num2.real)
print "Imaginary Part (comp_num2) :: {}".format(comp_num2.imag)
print "Complex Conjugate (comp_num2) :: {}".format(comp_num2.conjugate())

float_num = 11122.2
print "Float :: {}".format(float_num)

long_num = 111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111L
print "Long :: {}".format(long_num)

(3+13j)
<type 'complex'>
(2+5j)
Real Part (comp_num2) :: 2.0
Imaginary Part (comp_num2) :: 5.0
Complex Conjugate (comp_num2) :: (2-5j)
Float :: 11122.2
Long :: 111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111

Lists

list = [11,22,11,'hello']
list.append('22') # appending single element
print list

list.extend([55,'world'])  # appending more than 2 elements
print list

list.insert(1, 'MyList') # adding new element at a specific index
print list

print list[0:3] # Outputs first 3 elements

[11, 22, 11, 'hello', '22']
[11, 22, 11, 'hello', '22', 55, 'world']
[11, 'MyList', 22, 11, 'hello', '22', 55, 'world']
[11, 'MyList', 22]

list1=[1,2,3,4,5]
list2=[1,2,3]
list3=list1+list2
print list3 # Concatenating 2 lists

print list2*3 # prints list2 3 times itself

list3.sort() # Sorting Lists
print list3

print len(list3) # Counts length of list

list3.remove(1) # Removes 1st item whose value is equal to specified
print list3

[1, 2, 3, 4, 5, 1, 2, 3]
[1, 2, 3, 1, 2, 3, 1, 2, 3]
[1, 1, 2, 2, 3, 3, 4, 5]
8
[1, 2, 2, 3, 3, 4, 5]

list3.pop(6)  # Removes element at index 6
print list3

print list3.count(3) # Counts no. of times 3 appears

list3.reverse() # Reverses a list using function
print list3

print list1[::-1]  # Reverse a list by Slicing

[1, 2, 2, 3, 3, 4]
2
[4, 3, 3, 2, 2, 1]
[5, 4, 3, 2, 1]

for number in list3: # Iterating through a list
	print number,  # note the , for printing in a single line

4 3 3 2 2 1

Dictionaries

keyboard = {1:'CTRL', 2:'SHIFT', 4:'ENTER' }
print keyboard # lists contents of dictionary

print keyboard.values() # lists all values of all keys
print keyboard.keys() # gathers list all keys

{1: 'CTRL', 2: 'SHIFT', 4: 'ENTER'}
['CTRL', 'SHIFT', 'ENTER']
[1, 2, 4]

Accessing values

Output : SHIFT

I. Using key

print keyboard[2]

II. Using get()

print keyboard.get(2)

Deleting values

[(1, 'CTRL'), (4, 'ENTER')]

I. Using del

del keyboard[2]

II. Using pop()

keyboard.pop(2)

Some Useful Built-In Functions

print keyboard.items() # returns a *list of dict's (key,value) tuple pairs

dup = keyboard.copy() # duplicates a predefined dict
print dup

print keyboard.has_key(2) # Checks for a key in dict, Return bool

[(1, 'CTRL'), (4, 'ENTER')]
{1: 'CTRL', 4: 'ENTER'}
False

keys = {1,2,3}
value = 'NUMPAD'

kb2 = dict.fromkeys(keys, value) # Using fromkeys to create a dict from a sequence
print(kb2)

print len(kb2) # Counts the no. of (key,value) pair

print cmp(dup,kb2)
# returns 0 if both dictionaries are equal, -1 if kb2 < dup and 1 if kb2 > dup.

{1: 'NUMPAD', 2: 'NUMPAD', 3: 'NUMPAD'}
3
-1

keyboard.popitem() # pops out the first (key,value) pair
print keyboard

keyboard.clear() # Deletes every (key,value) pair present in the dictoinary
print keyboard

{4: 'ENTER'}
{}

Tuples

tuple1 = 1,2,3,4,5
tuple1 = (1,2,3,4,5)

print tuple1
print tuple1[4]

tuple2 = () # Declaring an Empty Tuple
print tuple2

tuple3 = 1,
print tuple3
print type(tuple3) # Checking data Type

(1, 2, 3, 4, 5)
5
()
(1,)
<type 'tuple'>

tuple4 = tuple('hello')
print tuple4

list1 = ['r','o','y']
tuple5 = tuple(list1) # Creating tuple from list
print tuple5

('h', 'e', 'l', 'l', 'o')
('r', 'o', 'y')

tuple6 = ('github') #Tuple with Loop
for i in range(3):
	tuple6 = tuple6,
	print tuple6

('github',)
(('github',),)
((('github',),),)

tuple7 = tuple4,tuple5 # Nesting Tuples
print tuple7

tuple8 = ('hi',) * 2
print tuple8

tuple8 += ('github',) # Concatenation
print tuple8

(('h', 'e', 'l', 'l', 'o'), ('r', 'o', 'y'))
('hi', 'hi')
('hi', 'hi', 'github')

numbers = (1,2,3)
a,b,c = numbers
print a

x, = 1,  # x is the value 1
print type(x)
x = 1,   # x is the tuple (1,)
print type(x)

1
<type 'int'>
<type 'tuple'>

# Slicing of a Tuple 
tuple9 = (10,20,30) 
print(tuple9[2:]) # Only Display 3rd Element
print(tuple9[::-1]) # Reversing the Tuple  
print(tuple9[1:3]) # Printing elements in a Range 

revTuple = tuple(reversed(('hello'))) #Reversing using reversed()
print revTuple

(30,)
(30, 20, 10)
(20, 30)
('o', 'l', 'l', 'e', 'h')

t1 = (11,22,33,44)
t2 = (19,22,44,45)
t3 = (11,22,33,44)
t4 = ('a','b','c','d','e')

print cmp(t1,t2) # Returns '-1' as t2's elements are greater than t1's
print cmp(t1,t3) # Returns '0' as both tuples have exactly same elements 
print cmp(t4,t1) # Returns '1' as numbers is considered smaller than chars

-1
0
1

t1 = (1, 0, 2, 5, 4, 2, 4)
t2 = ('a','b','bee','bug')
print len(t1) # Counts no. of elements
print t1.count(2) # Counts the no. of times an element appears in tuple

7
2

print max(t1) # Numbers sorting
print max(t2) # Sorting Alphabetically

print min(t1) 
print min(t2)

5
bug
0
a

# sum()	Sums up the numbers in the tuple
print sum(t1)

print sorted((66,234,20)) # Returns sorted list

18
[0, 1, 2, 2, 4, 4, 5]

# all() Returns true if all element are true or if tuple is empty

l = [1, 3, 4, 5]  # all values true
print all(l)

l = [0, False] # all values false
print all(l)

l = [1, 3, 4, 0] # one false value
print all(l)

l = [0, False, 5]  # one true value
print all(l)

l = [] # empty iterable
print all(l)

True
False
False
False
True

# any() Returns true if any element of the tuple is true, also false if tuple empty 
l = [1, 3, 4, 0]
print(any(l)) 

l = [0, False]
print(any(l))

l = [0, False, 5]
print(any(l))

l = []
print(any(l))

True
False
True
False

#map() applies a given function to each item of an iterable and returns a list with result.
def Square(n):
  return n*n

numbers = (1, 2, 3, 4)
sqList = map(Square, numbers)
print sqList

[1, 4, 9, 16]

t1 = (1,2,3)
del t1 
print t1

print t1
NameError: name 't1' is not defined

Random File Operations

import base64

# Using a list to read line by line 
with open('random.txt','r+') as fl: # Read & Write both with 'r+'
	contentList = fl.readlines()
	beLine = base64.b64encode(str(contentList[3])) # base64 encodes the 4th item in list
	if (contentList[-1] != beLine):	# Check if last line not encoded
	 fl.write("\n"+beLine) # If not encoded then encode it and write to the file

# Another method -- Simply Read as Strings (for Small Files)
with open('random.txt', 'r') as fl:   
	content = fl.read()  

#Decoding the last line which was encoded by us
print content + " when decoded gives :: " + base64.b64decode(str(contentList[-1]))

hi
hello
hola
hey
aGV5Cg== when decoded gives :: hey

mrT4ntr4/My-Python-Register

My Python Register

Help about a module

To Check BuiltIn Functions in a module

Importing Modules

Strings

Ways to Concatenate string and int

I. Using str() fn.

II. Using % Operator

III. Using format function

Sets, FrozenSets and MultiSets

Complex Numbers and other data types

Lists

Dictionaries

Accessing values

I. Using key

II. Using get()

Deleting values

I. Using del

II. Using pop()

Some Useful Built-In Functions

Tuples

Random File Operations