Remove values / nan / empty string("") from list of lists in python

Question

Given:

a = [["a","",""],
 ["b","",""],
 ["c","d",""]]

b = [["a", nan, nan],
["b", nan, nan],
["c","d", nan]]

I would like to remove the value which is nan or empty string.

This is my current code:

while("" in a):
    a.remove("")

and

b = [x for x in b if str(x) != nan]

but both don't work, what should I do?

a is a list-of-lists. "" is not a direct member of a. — John Gordon
– John Gordon, Commented Sep 26, 2019 at 2:33
@Chris is NaN in the excel before i change it to list ,so I guess is numpy.nan — YTPan
– YTPan, Commented Sep 26, 2019 at 2:46

GZ0 · Accepted Answer · 2019-09-26 02:53:52Z

1

Here is the corrected version.

from math import isnan  # numpy.isnan can also be used instead

# If the list contains only strings, `if e != ""` can be simplied to `if e`
a = [[e for e in l if e != ""] for l in a]

# Use isnan function to check for nan values
b = [[e for e in l if not isnan(e)] for l in b]

answered Sep 26, 2019 at 2:53

GZ0

4,2881 gold badge12 silver badges23 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Alec · Accepted Answer · 2019-09-26 02:31:58Z

0

x for x in b only looks at list level 1.

Try this:

b = [[n for n in b] for x in b if n not in ('nan', "")]

answered Sep 26, 2019 at 2:31

Alec

9,7338 gold badges44 silver badges71 bronze badges

Comments

qloveshmily · Accepted Answer · 2019-09-26 02:55:06Z

0

list.remove("") removes the first "" element in list. a doesn't contain "". You should do it for every sublist in a or b.

for l in a:
    while "" in l:
        l.remove("")

answered Sep 26, 2019 at 2:55

qloveshmily

1,06910 silver badges5 bronze badges

Collectives™ on Stack Overflow

Remove values / nan / empty string("") from list of lists in python

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related