Remove zero after first space pandas regex

Question

I have a dataframe like this:

df = 

number
+123 1234
+123 0123
+123+123 01234
+123 0123 0023

I want to remove only 0 only after first space as a new column. Desired output:

number            filtered
+123 1234         +123 1234
+123 0123         +123 123
+123+123 01234    +123+123 1234
+123 0123 0023    +123 123 0023

My try is:

df['filtered'] = df['number'].replace(r'\s(.)', '', regex=True)

But I realized that it is removing first character after space not only zero

I am ok even with different approach, not regex only

score 2 · Accepted Answer · answered Oct 14 '22 at 06:09

2

You can use this regex to match from beginning of line up to a zero 0 after the first space, and then replace the match with capture group 1:

^(\S*\s)0

In python:

df['filtered'] = df['number'].replace(r'^(\S*\s)0', r'\1', regex=True)

Output:

    +123 1234
     +123 123
+123+123 1234
+123 123 0023

answered Oct 14 '22 at 06:09

Nick

Thanks! I found that regex is powerful thing. Where I can read about documentation or combinations of this elements to get desired result? – Mamed Oct 14 '22 at 06:16
@Mamed there's a good reference q&a [here](https://stackoverflow.com/questions/22937618/reference-what-does-this-regex-mean) and a good tutorial [here](https://www.regexbuddy.com/tutorial.html) and I highly recommend playing with regexes on sandbox sites such as [regex101](https://regex101.com) – Nick Oct 14 '22 at 06:20

score 1 · Answer 2 · answered Oct 14 '22 at 06:22

1

Try this

\s0

Python

df['filtered'] = df['number'].replace(r'\s0', ' ', regex=True)

answered Oct 14 '22 at 06:22

Pranjal Patel

Notice that your regex filters out one extra `0` in the bottom row: `initial: +123 0123 0023`, `expected: +123 123 0023`, `yours: +123 123 023`. This happened because you coded to remove any `0` preceded by whitespace in a row. – Nikita Shabankin Oct 18 '22 at 01:30

2 Answers2