Python: For every 2 items in list?

Question

The default for loop only iterates through each item at a time. How can I make it so I can iterate through every 2 items?

Do you mean every other item, every non-overlapping pair, or every overlapping pair? — Davis Herring, Aug 25 '19 at 22:14

score 4 · Accepted Answer · answered Aug 25 '19 at 22:16

4

You can use the slice notation:

for item in items[::2]:
   print(item)

If you want to iterate pairwise every 2 items, you can do this:

for item1, item2 in zip(items[::2], items[1::2]):
   print(item1, item2)

answered Aug 25 '19 at 22:16

zdimension

score 1 · Answer 2 · answered Aug 25 '19 at 22:15

1

you can use:

for item in items[::2]:
   <your_code>

answered Aug 25 '19 at 22:15

kederrac

score 0 · Answer 3 · answered Aug 25 '19 at 22:14

0

for idx, item in enumerate(items):
    if idx % 2 == 1:
        // do something

answered Aug 25 '19 at 22:14

greentec

1

Why not use the slice notation? `items[::2]` would be more Pythonic – zdimension Aug 25 '19 at 22:15
Yes, if we don't need to access the index, that might be a better way. – greentec Aug 25 '19 at 22:17
@zdimension: There is sometimes a reason to not copy (even half of) the input. – Davis Herring Aug 25 '19 at 22:26

score 0 · Answer 4 · answered Aug 25 '19 at 22:15

0

The following will iterate over every two items:

for i in range(0,20,2):
    print(i)

answered Aug 25 '19 at 22:15

Neeraj Agarwal

ardms · Answer 5 · 2019-08-25T22:23:05.397

0

Assuming you are talking about a list. Then You can use the slice notation

data = [1,2,3,4,5,6]
for i in data[::2]:
...     print(I)

edited Aug 25 '19 at 22:23

answered Aug 25 '19 at 22:16

ardms

5 Answers5