Update Pandas df Given String Query

Question

As a result of data introduced by users in the interface I have a string query-like.

query = '(ColA=="7") & (ColB=="3") & (ColC=="alpha") & (ColD=="yu")'

Now I want to update a column of the df based on those conditions, assigning it a variable Z.

I don't know if it can be done somehow with loc

df.loc[query, 'ColZ'] = Z

score 5 · Answer 1 · edited Aug 11 '22 at 03:58

5

Yes that can be done with query

df.loc[df.query(query).index,'ColZ']=Z

edited Aug 11 '22 at 03:58

Attila the Fun

answered May 23 '20 at 22:49

BENY

score 0 · Accepted Answer · answered May 24 '20 at 11:51

0

I got the solution by myself:

df.loc[df.eval(query), 'ColZ'] = Z

answered May 24 '20 at 11:51

burn1000

eval is a dangerous coding practice. query method is better – Tyn Jul 27 '22 at 16:40

2 Answers2