Replace start or end of string in values of pandas column with regex-CodePudding

With sed, I can do

$ sed 's/^/prefix/' <<EOF
> foo
> EOF
prefixfoo

When I use pandas.Series.str.replace, the regex does not work. The minimal working example

import pandas as pd

df = pd.DataFrame({"text": ["foo", "bar"]})
df.text.str.replace("^", "prefix", regex=True)

returns

0    foo
1    bar
Name: text, dtype: object

CodePudding user response：

It works if you capture the ^:

df['text'].str.replace(r'(^)', 'prefix', regex=True)

Output:

0    prefixfoo
1    prefixbar
Name: text, dtype: object

That said the best method to prepend a string would be to concatenate:

'prefix' df['text']