Save iteration number during a for loop in python

Question

I have a list of arrays that I am iterating over with python, so the head of my loop looks like:

for item in my_long_list:
     do_something

My problem is that I want to save the iteration number, so that info can be extracted from another array, something like:

for item in my_long_list:
    do_something
    grab_values(another_long_list[i])

where i is he iteration number that the loop is going through at that moment.

I thought about doing a nested loop like:

for i in list(range(1,len(my_long_list)):
    for item in my_long_list:
        do_something
        grab_values(another_long_list[i])

but it repeats i for each one of the items, when in reality what I want is one single iteration number per item in my long list.

So is there a way to "store" the iteration number and use it within the loop with python?

I think you are talking about the enumerate function docs.python.org/2.3/whatsnew/section-enumerate.html — Mntfr
– Mntfr, Commented Jun 12, 2020 at 2:59

NotAName · Accepted Answer · 2020-06-12 03:00:46Z

4

You can use the enumerate method that returns the tuple of item number and value.

for iter, i in enumerate(my_long_list)):
    for item in my_long_list:
        do_something
        grab_values(another_long_list[iter])

answered Jun 12, 2020 at 3:00

NotAName

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Comments

Jun · Accepted Answer · 2020-06-12 03:29:47Z

1

if you want current item number, maybe you can do this:

for i, v in enumerate(my_long_list,1): # item number from 1 start
    do_something
    grab_values(another_long_list[i])

answered Jun 12, 2020 at 3:29

Jun

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