populate empty list elements with strings python

Question

I have a dataframe which contians nested lists. Some of those lists are empty, or contain only whitespaces. e.g:

df=pd.DataFrame({'example':[[['  ', ' '],['Peter'],['   ', ' '],['bla','blaaa']]]})

for my further operations they are not allowed to be empty and cannot be deleted. Is there a way to fill them with e.g. 'some_string

i thought of something similar to df.example = [[[a.replace(' ','some_string')if all a in i =='\s'for a in i]for i in x] for x in df.example], but this yields an invalid syntax error, further it wouldnt just fill the list, but each whitespace in the list. Since i am still learning python, my idea of a solution might be too complicated or completely wrong.

i.e. the solution should look like:

     example
0   [[some_string], [Peter], [some_string], [bla, blaaa]

Rakesh · Accepted Answer · 2019-07-15 10:54:55Z

2

Using apply

Ex:

df=pd.DataFrame({'example':[[['  ', ' '],['Peter'],['   ', ' '],['bla','blaaa']]]})
df["example"] = df["example"].apply(lambda x: [i if "".join(i).strip() else ['some_string'] for i in x])
print(df)

Output:

                                             example
0  [[some_string], [Peter], [some_string], [bla, ...

Note: This will be slow if you data is very large because of the iteration.

answered Jul 15, 2019 at 10:54

Rakesh

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1 Comment

jezrael Over a year ago

Or df.example = [[i if ''.join(i).strip() else ['some_string'] for i in x] for x in df.example]

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