Python List Comprehension: Find common numbers in two lists of numbers

common_nums.py

'''
Find the common numbers in two lists (without using a tuple or set) list_a = [1, 2, 3, 4], list_b = [2, 3, 4, 5]

'''
list_a = [1, 2, 3, 4]
list_b = [2, 3, 4, 5]
common = [a for a in list_a if a in list_b]
print(common)

But if you use repeated numbers on the list or lists of different length, is not going to work very well, I prefer to use the set, even if you say "without using a set".
print (set (a for a in list_a if a in list_b) )

I guess he said 'without using a set' because using a set, this is easily achievable by using intersection. There's no need for a comprehension.

using nested loops

list_a = 1, 2, 3, 4
list_b = 2, 3, 4, 5
my_list = [element_b for element_b in list_b for element_a in list_a if element_b == element_a]
print(my_list)

using nested loops and function in the expression of list comprehension for it wouldn't add repeated numbers. Though it might be confusing

common_numbers = []
def f(x):
    common_numbers.append(x)
    return x

list_a = 1, 2, 3, 4, 
list_b = 2, 3, 4, 5,
my_list = [f(element_b) for element_b in list_b for element_a in list_a if element_b == element_a and element_b not in common_numbers]
print(my_list)

list_a=1,2,3,4
list_b=2,3,4,5
list=[i for i in list_a for j in list_b if i==j]
Print(list)

list_a = [1,2,3,4]
list_b = [2,3,4,5]
common_numbers = [n for n in list_a if n in list_b]
print("Common numbers: ",common_numbers)

list_a = [1,2,3,4]
list_b = [2,3,4,5]
common_number = [num for num in list_b if num in list_a]
print(common_number)