How do I apply a regex substitution in a string column of a DataFrame?

Question

I have a DataFrame called "Animals" that looks like this:

 Words
 The Black Cat
 The Red Dog

I want to add a plus sign before each word so that it looks like this:

 Words
 +The +Black +Cat
 +The +Red +Dog

I have tried this using regex but it did not work:

 df = re.sub(r'([a-z]+)', r'+\1', Animals)

Alex Riley · Accepted Answer · 2015-09-09 19:17:38Z

7

You can use str.replace with the following regex to make the change to all rows of the column:

df.Words = df.Words.str.replace(r'(\b\S)', r'+\1')

The DataFrame then looks like this:

>>> df
              Words
0  +The +Black +Cat
1    +The +Red +Dog

answered Sep 9, 2015 at 19:17

Alex Riley

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2 Comments

user3682157 Over a year ago

Very good, thank for for the solution. I know not part of the original question but was wondering whether this could also be adapted to remove white space between words?

Alex Riley Over a year ago

@user3682157: no problem, glad it helped. To remove all of the whitespace you could perhaps use df.Words.str.replace(r'\s', r'').

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