Pandas loc multiple conditions

Question

I have a dataframe and I want to delete all rows where column A is equal to blue and also col B is equal to green.

I though the below should work, but its not the case.

Can anyone see the problem

df=df.loc[~(df['A']=='blue' & df['B']=='green')]

`df.loc[~((df['A']=='blue') & (df['B']=='green'))]` , `()` is the problem — anky, Jul 04 '19 at 15:32

score 12 · Accepted Answer · answered Jul 04 '19 at 15:37

12

You should separate the two propositions:

df1=df.loc[~(df['A']=='blue') & ~(df['B']=='green')]

answered Jul 04 '19 at 15:37

Jim Eisenberg

score 7 · Answer 2 · answered Jul 04 '19 at 15:32

7

use eq instead of ==:

df.loc[~(df['A'].eq('blue') & df['B'].eq('green'))]

answered Jul 04 '19 at 15:32

Quang Hoang

3

this prevents you from [operator precedence](https://stackoverflow.com/questions/20333435/pandas-comparison-raises-typeerror-cannot-compare-a-dtyped-float64-array-with) : Note to OP :) – anky Jul 04 '19 at 15:49
1

Nice comment @anky_91 (-: – piRSquared Jul 04 '19 at 15:54

score 4 · Answer 3 · answered Jul 04 '19 at 15:51

4

Note the != and or as consequence of De Morgan's Law

df.query('A != "blue" or B != "green"')

answered Jul 04 '19 at 15:51

piRSquared

3 Answers3