Pandas trim leading & trailing white space in a dataframe

Question

develop a function that Trims leading & trailing white space.

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'])

Answer 1

I think there is a one-liner for that using regex and replace:

df = df.replace(r"^ +| +$", r"", regex=True)

Answer 2

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 NaN s 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