Comparing two lists element-wise in python [duplicate]

Question

I have two list

first= (1,2,3,4,5,6)
last=(6,5,4,3,2,1)

I need to compare the corresponding values only. I have used the below code and getting 36 results as the 1st element in first is comparing with all the six elements of last list.

for x in first:
    for y in last:
        if x>y:
            print("first is greater then L2",y)
        elif x==y:
            print("equal")
        else:
            print("first is less then L2",y)

irst= (1,2,3,4,5,6)
last=(6,5,4,3,2,1)
for x in first:
    for y in last:
        if x>y:
            print("first is greater then L2",y)
        elif x==y:
            print("equal")
        else:
            print("first is less then L2",y)

output:

L1 is less then L2 6
L1 is less then L2 5
L1 is less then L2 4
L1 is less then L2 3
L1 is less then L2 2
go dada
L1 is less then L2 6
L1 is less then L2 5
L1 is less then L2 4
L1 is less then L2 3
go dada
L1 is greater then L2 1
L1 is less then L2 6
L1 is less then L2 5
L1 is less then L2 4
go dada
L1 is greater then L2 2
L1 is greater then L2 1
L1 is less then L2 6
L1 is less then L2 5
go dada
L1 is greater then L2 3
L1 is greater then L2 2
L1 is greater then L2 1
L1 is less then L2 6
go dada
L1 is greater then L2 4
L1 is greater then L2 3
L1 is greater then L2 2
L1 is greater then L2 1
go dada
L1 is greater then L2 5
L1 is greater then L2 4
L1 is greater then L2 3
L1 is greater then L2 2
L1 is greater then L2 1
y

I need results by comparing the corresponding elements only. Which means there should be only six outputs.

Answer 1

first and last are tuples, not lists (lists elements are within square brackets like [1,2,3]).

You can use zip(first,last) to create a list of pairs from the two tuples:

[(1, 6), (2, 5), (3, 4), (4, 3), (5, 2), (6, 1)]

then iterate over the tuples and compare each pair:

first = (1,2,3,4,5,6)
last = (6,5,4,3,2,1)

for l1,l2 in zip(first,last):
    if l1 < l2:
        print("l1 < l2")
    elif l1 > l2:
        print("l2 > l1")
    elif l1 == l2:
        print("l1 == l2")

Output:

l1 < l2
l1 < l2
l1 < l2
l2 > l1
l2 > l1
l2 > l1

Another approach would be to iterate over the indices, however this approach is less Pythonic:

for i in range(len(first)):
    l1 = first[i]
    l2 = last[i]
    if l1 < l2:
        print("l1 < l2")
    elif l1 > l2:
        print("l2 > l1")
    elif l1 == l2:
        print("l1 == l2")