How to delete empty strings from a 2d list

Question

I have this 2d list right here :

list = [ [1,2,3], [1,'',''], ['','','']]

I want to delete every instance of '' in the list, so that the output should look like this:

>> [ [1,2,3],[1]]

I think that deleting all the ''-s is gonna left me out with this list, so could you please also explain how to get rid of empty lists in 2d lists?

>> [ [1,2,3],[1],[]]

Thank you!

You should check for list's length after you did your first iteration, but it's really hard to give an answer if you don't share what you already tried. — Pooya Mobasher Behrooz, Sep 17 '19 at 23:47
Possible duplicate of [Remove empty strings from a list of strings](https://stackoverflow.com/questions/3845423/remove-empty-strings-from-a-list-of-strings) — Mr. J, Sep 17 '19 at 23:59

score 3 · Accepted Answer · answered Sep 17 '19 at 23:51

3

a = [[1,2,3], [1,'',''], ['','','']] 
b = [[i for i in item if i != ''] for item in a]
c = [item for item in b if item != []]
print(b)
print(c)

Output

[[1, 2, 3], [1], []]
[[1, 2, 3], [1]]

answered Sep 17 '19 at 23:51

could you please explain how this works? b = [[i for i in item if i!=''] for item in a]. – sleeping_with_fishes Sep 17 '19 at 23:54
It selects all the none `''` element in the nested list. – ComplicatedPhenomenon Sep 17 '19 at 23:58
oh, i get it. So what you do is you have a nested loop for items in list, and another loop for the whole list. Thank you so much. – sleeping_with_fishes Sep 17 '19 at 23:59

score 1 · Answer 2 · answered Sep 17 '19 at 23:55

1

could also use filter:

lst = [ [1,2,3], [1,'',''], ['','','']] #don't use list to define a list
list(filter(None,[list(filter(None,l)) for l in lst]))

output:

[[1, 2, 3], [1]]

answered Sep 17 '19 at 23:55

Derek Eden

score 0 · Answer 3 · answered Sep 17 '19 at 23:53

0

A one liner with nested list comprehensions (not very dry though):

[[y for y in x if y != ''] for x in list if [y for y in x if y != ''] != []]
# [[1, 2, 3], [1]]

answered Sep 17 '19 at 23:53

AidanGawronski

3 Answers3