python - Pandas trim leading & trailing white space in a dataframe

Question

develop a function that Trims leading & trailing white space.

here is a simple sample, but real file contains far more complex rows and columns.

df=pd.DataFrame([["A b ",2,3],[np.nan,2,3],
[" random",43,4],[" any txt is possible "," 2 1",22],
["",23,99],[" help ",23,np.nan]],columns=['A','B','C'])

the result should eliminate all leading & trailing white space, but retain the space inbetween the text.

df=pd.DataFrame([["A b",2,3],[np.nan,2,3],
["random",43,4],["any txt is possible","2 1",22],
["",23,99],["help",23,np.nan]],columns=['A','B','C'])

Mind that the function needs to cover all possible situations. thank you

Answer 1

I think need check if values are strings, because mixed values in column - numeric with strings and for each string call strip:

df = df.applymap(lambda x: x.strip() if isinstance(x, str) else x)
print (df)
                     A    B     C
0                  A b    2   3.0
1                  NaN    2   3.0
2               random   43   4.0
3  any txt is possible  2 1  22.0
4                        23  99.0
5                 help   23   NaN

If columns have same dtypes, not get NaNs like in your sample for numeric values in column B:

cols = df.select_dtypes(['object']).columns
df[cols] = df[cols].apply(lambda x: x.str.strip())
print (df)
                     A    B     C
0                  A b  NaN   3.0
1                  NaN  NaN   3.0
2               random  NaN   4.0
3  any txt is possible  2 1  22.0
4                       NaN  99.0
5                 help  NaN   NaN