unpacking multiple arguments from a list in a for loop

Question

I have two lists.

d1 = ["'02/01/2018'", "'01/01/2018'", "'12/01/2017'"]
d2 = ["'02/28/2018'", "'01/31/2018'", "'12/31/2017'"]

I am trying to get these values to be unpacked in a for loop.

for i,y in d1,d2:
    i,y = Startdate, Enddate

I realize this iteration will overwrite the values for Startdate and Enddate with each iteration but for now i'm just trying to successfully unpack the elements of each list.

I get the following error:

too many values to unpack (expected 2)

I thought I was unpacking 2? (d1 and d2)

`d1,d2` creates a tuple with two elements, your lists... each of your lists has three elements, which it tries to unpack into `i,y` — juanpa.arrivillaga, Aug 29 '18 at 18:17

Nouman · Answer 1 · 2018-08-29T20:09:00.093

4

You need to use zip. Here is an experiment with zip:

>>> a = [1,2,3]
>>> b = [4,5,6]
>>> for i,y in zip(a,b):
    print(i,y)

1 4
2 5
3 6
>>>

You can say that your loop can be like:

for i,y in zip(d1,d2):
    i,y = Startdate, Enddate

edited Aug 29 '18 at 20:09

answered Aug 29 '18 at 18:19

Nouman

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score 0 · Answer 2 · answered Aug 29 '18 at 18:25

0

The for loop cannot "unpack" several list as you tried in you example, but you can 'zip' it as mentionner by @Nouman

list(zip([1, 2, 3], ['a', 'b', 'c'])) --> [(1, 'a'), (2, 'b'), (3, 'c')]

You can now unpack the dates two per two...

answered Aug 29 '18 at 18:25

Fabrice LARRIBE

322
3
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unpacking multiple arguments from a list in a for loop

2 Answers2