Pandas UserWarning 根据条件使用 df.loc 时

Question

I've below dataframe where I want to change values based on condition

    name    checker data
0  user1  user122AB   10
1  user2  user132AB   12
2  user3  user346AB   14
3  user4  user108AB   16
4  user5  user122CD   10
5  user6  user132CD   12
6  user7  user346CD   14
7  user8  user108CD   16

Expected output:

    name    checker data
0  user1  user122AB   10
1  user2  user132AB   12
2  user3  user346AB   14
3  user4  user108AB   16
4  user5  user122CD  900
5  user6  user132CD  900
6  user7  user346CD  900
7  user8  user108CD  900

I'm using below code for same.

import pandas as pd
import re

df = pd.DataFrame([["user1", "user122AB", "10"], ["user2", "user132AB", "12"], ["user3", "user346AB", "14"], ["user4", "user108AB", "16"], ["user5", "user122CD", "10"], ["user6", "user132CD", "12"], ["user7", "user346CD", "14"], ["user8", "user108CD", "16"]], columns=["name", "checker", "data"])
df.loc[df.checker.str.contains("\d+\w*(CD)$"), "data"] = "900"
print(df)

It is doing the exact thing that I want but throwing below warning along with output.

UserWarning: This pattern has match groups. To actually get the groups, use str.extract.

Please help if I'm doing something wrong or please share any better way to achieve this.

Answer 1

You have this warning because of the parenthesis. You are searching for matching patterns, to be returned. I think this is unnecessary. pandas (1.0.3) is coded to send a warning is the regex match one ore more parenthesis patterns ( if regex.groups > 0: warnings.warn(...) ).

The line below is then working without warning:

df.loc[df.checker.str.contains("\d+\w*CD$"), "data"] = "900"