Strip space from all column values in Pandas

Question

I was working on a problem set where we have a lot of columns in a Pandas dataframe and many of these columns have trailing spaces. My question is, is there a better way to remove these spaces rather than creating a dynamic string (where we pass in column name as variable and append a strip() to it) and then executing it for every column.

Answer 1

Without an example it is not fully clear what you want to accomplish, but maybe the following will help:

import pandas as pd

df = pd.DataFrame({'A  ': [1, 2], 'B ': [4, 5], 'C': [8,9]})

The column headers do have trailing white spaces:

df.columns
Index([u'A  ', u'B ', u'C'], dtype='object')

Now you can use map and strip to get rid of them:

df.columns = df.columns.map(lambda x: x.strip())

or alternatively

df.columns = df.columns.map(str.strip)

or simply (which should be the preferred option)

df.columns = df.columns.str.strip()

If you now call

df.columns

it yields

Index([u'A', u'B', u'C'], dtype='object')

If it is about the values and not the headers, you can also use applymap:

df = pd.DataFrame({'A': ['1', '2  '], 'B': ['4 ', '5 '], 'C': ['8 ','9']})

     A   B   C
0    1  4   8 
1  2    5    9

Then the following gets rid of the trailing white spaces:

df.applymap(lambda x: x.strip())

or alternatively (which is the better option):

df.applymap(str.strip)

   A  B  C
0  1  4  8
1  2  5  9

Note: This assumes, that you have only strings in your columns. You can also check this link.