Sublists from a python list such that first sublist contains first 2 elements of list, then first 3 elements and so on and Num as 3rd, 4th and so on

Question

From a given list, I have to create sublists that follow a sequence as first 2 elements, then first 3 elements, then first 4 elements and so on from the given list and corresponding num as 3rd element, 4th element, 5th element, and so on. Used the below-given code, but it is not giving the 0 indexed list element i.e. 1. What’s wrong?

list = [1, 3, 2, 10, 4, 8, 6]
list2 = []
Num = None
for i in range(2,len(list)):
    print(f"i = {i}")
    Num = list[i]
    for j in range(0,i):
        print(f"j = {j}")
    list2.append(list[j])
    print(f"tlist2 = {list2}tNum = {Num}")
    print(f".........................................................")

Desired Output:

list2 = [1, 3]  Num = 2
list2 = [1, 3, 2]  Num = 10
list2 = [1, 3, 2, 10]   Num = 4
list2 = [1, 3, 2, 10, 4]    Num = 8
list2 = [1, 3, 2, 10, 4, 8]   Num = 6

Asked By: sanjay tewari

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Source

Answer 1

try changing

for i in range(2,len(list)):

condition to

for i in range(1,len(list)):

so the loop would start on the first element of the given list. This should solve the problem.

Answered By: Alex Iovin

Answer 2

a = [1, 3, 2, 10, 4, 8, 6]

for i in range(2,len(a)):
    print(f'list2 = {a[:i]} Num={a[i]}')

Output

list2 = [1, 3] Num=2
list2 = [1, 3, 2] Num=10
list2 = [1, 3, 2, 10] Num=4
list2 = [1, 3, 2, 10, 4] Num=8
list2 = [1, 3, 2, 10, 4, 8] Num=6

Answered By: Mazhar

Sublists from a python list such that first sublist contains first 2 elements of list, then first 3 elements and so on and Num as 3rd, 4th and so on

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