. List, Sets, Tuple & Dictionary Operations

# accessing element in a nested list 
sample_list = [["Hello","world"],["we are learning python"]]
print(sample_list[0][1])
print(sample_list[0][1][:3])

# get 3rd elment from the last in a list
sample_list = [20,21,22,23,24,25]
print(sample_list[-3])

# length of a list 
len(sample_list)

# adding an element to a list
print(f"list before adding an element {sample_list}")
sample_list.append('a')
print(f"list after adding an element {sample_list}")

# if you want to add element at any specific index (provide index and the value) all the values will be shifted to right of 
# the list 
sample_list.insert(0,'b')
sample_list

# concateing two list
list1 = ['a','b','c']
list2 = ['d','e','f']
print(list1+list2)

# reversing a list
print(list1[::-1]) # method 1
list1.reverse() # method 2 actual string will be changes 
print(list1)

# remove an element from list
list1=['a','b','c']
list1.remove('c')
list1

# remove element using pop method
list1=['a','b','c']
list1.pop() # pop is used without index last element will be removed 
print(list1)
list1=['a','b','c']
list1.pop(0) # pop is used without index last element will be removed 
print(list1) # if pop is used with index the element of index will be removed

# slicing dicing a list 
list1=['a','b','c',1,2,3,4,5]
print(list1[1:]) # get all the element after 1 index inclding 1 
print(list1[:5]) # get all element before 5th index 
print(list1[-4]) # get 4th element from end of the list 

# List comprehension - writing for in a list 
l=[10,9, 1, 2, 3, 4, 5]
for i in l :
    print(i) # instead of this we can wrie below statement
print("Simple list comprehension")
print([i for i in l]) # simple list comprehension 
print("list comprehension with transformations")
print([i*2 for i in l]) # simple list where each element is doubled 
print("list comprehension with transformations and filter")
print([i*2 for i in l if i%2==0]) # list comprehension with filter 

# nested list comprehension 
l=[[10,9, 1, 2, 3, 4, 5],[10,9, 1, 2, 3, 4, 5],[10,9,4, 5]] # doubling each element of the sublist
[[j*2 for j in i] for i in l]

# get the frequency of an element is a list
sample_list.count(22)

# arithmatic operations like max , min, sum,len are also possible 
sample_list=[20, 18, 2, 4, 6, 8, 10]
print(sum(sample_list))
print(min(sample_list))
print(max(sample_list))
print(len(sample_list))

# adding element to a set- since sets are mutable new elements can be added to it, but item assignment is not possible , since 
# sets are unorder

sample_set={1,2,3,5,8,10}
print("Before adding ",sample_set)
sample_set.add('12')
print("After adding ",sample_set)

# sets can only have unique value 
sample_set={1,2,3,5,8,10}
sample_set.add(1) # adding 1 again will not duplicate the values in a set
sample_set

# union operation in sets
sample_set_1={1,2,3,4,5}
sample_set_2={4,5,6,7,8} # notince that 4 and 5 are common in 2 sets 
sample_set_1.union(sample_set_2)# the new set will have all the variables but without duplicates

# intersection operation in sets
sample_set_1={1,2,3,4,5}
sample_set_2={4,5,6,7,8} # notince that 4 and 5 are common in 2 sets 
sample_set_1.intersection(sample_set_2)# the new set will have all only common variable in 2 sets 

# finding difference in two sets
sample_set_1={1,2,3,4,5}
sample_set_2={4,5,6,7,8} # notince that 4 and 5 are common in 2 sets 
sample_set_1.difference(sample_set_2)# values in 1 which are not present in set 2

# Operators with set 
sample_set_1={1,2,3,4,5}
sample_set_2={5,4,3,2,1} # since sets are inordered below 2 sets are equal 
sample_set_1==sample_set_2

# inequality, subset and superset can also be checked in sets 
sample_set_1={1,2,3,4,5}
sample_set_2={4,3,2,1} # since sets are inordered below 2 sets are equal 
print("Checking inequality")
print(sample_set_1!=sample_set_2 )# checking inequality in sets

print("Checking subset")
print(sample_set_1<=sample_set_2 )# checking subset

print("Checking superset")
print(sample_set_1>=sample_set_2 )# checking superset

import random

sample_tuple=tuple([random.randint(1,100) for x in range(100)])
# tuples are index and slicing dicing like a list is also possible

print(sample_tuple[4]) # access 4th element
print(sample_tuple[4:10]) # access element from index 4 to 10
print(sample_tuple[:10]) # access element from index 0 to 10
print(sample_tuple[10:]) # access element from index 10 to last
print(sample_tuple[::-1]) # reverse a tuple

# concat two tuples 
sample_tuple_1=tuple([random.randint(1,10) for x in range(100)])
sample_tuple_2=tuple([random.randint(1,10) for x in range(100)])
print(len(sample_tuple_1+sample_tuple_2))

# get first index of a value in tuple 
print(sample_tuple_1.index(2))

# get freq of an element in a tuple  
sample_tuple_1.count(2)

# operations like max , min, sum,len are also possible 
sample_tuple_1=(20, 18, 2, 4, 6, 8, 10)
print(sum(sample_tuple_1))
print(min(sample_tuple_1))
print(max(sample_tuple_1))
print(len(sample_tuple_1))

# get all key and values of a dict 
sample_dict={'a':1,'b':2,'c':3,'d':4}
print("Keys -->",sample_dict.keys())
print("values -->",sample_dict.values())

# remove the element using a given key 
print("Before removing element")
sample_dict={'a':1,'b':2,'c':3,'d':4}
print(sample_dict)
print("After removing element")
sample_dict.pop('a')
print(sample_dict)

# iterator over keys and values together
# method 1
for k,v in zip(sample_dict.keys(),sample_dict.values()):
    print(f"For key {k} the value is {v}")

# method 2 using list comprehension
[f"for key {k} the values is {v}" for k,v in sample_dict.items()]

# Example 1 - create a dict from a list where keys are values of list and values are count of that value in list
sample_list=[random.randint(1,10) for x in range(100)]
final_dict={}
for i in sample_list:
    if i in final_dict.keys():
        final_dict[i]=final_dict[i]+1
    else:
        final_dict[i]=1
final_dict

# Example 2 -  Write a Python function to remove duplicates from a list and return the unique elements.
sample_list=[random.randint(1,10) for x in range(100)]
# method 1 - using loop
final_list=[]
for i in sample_list:
    if i in final_list:
        pass 
    else:
        final_list.append(i)

# method 2 - using set 
list(set(sample_list))