Python - How to get first item in list on list in python3

Question

I have a list in python like the following:

edge =  [[1, 2], [1, 3], [1, 4], [3, 4]]

I want to print 1 and 1 and 1 and 3; aka the first element of each sub-list.

I use this code:

for subList in edge:
    for firstItem in subList:
        print(firstItem)

But it prints all elements..

Answer 1

You are looping over all elements of all nested lists. If you only wanted to print the first element of each nested list, use indexing:

for sublist in edge:
    print(sublist[0])

If all nested lists have the same number of elements you could use unpacking:

for start, end in edge:
    print(start)