condition error in loc in python

Question

I have a following date frame.

mydf = pd.DataFrame({'month':[2,3,7,8],'day':[29,24,20,29]})
>>> mydf
   day  month
0   29      2
1   24      3
2   20      7
3   29      8

>>> leapdf =  mydf.loc[(mydf['month'] == 2) & (mydf['day'] == 29) ]
>>> leapdf
   day  month
0   29      2

>>> otherdf =  mydf.loc[(mydf['month'] != 2) & (mydf['day'] != 29) ]
>>> otherdf
   day  month
1   24      3
2   20      7

Above otherdf I am expecting day 29 and month 8 to be included. But not included. Can any one guide me what is the error.

Thanks

Why would you expect day 29 to be included when you explicitly denied it? (mydf['day'] != 29). Your filter removes all months of Feb and all days (regardless of month) equal to day 29. — Alexander
– Alexander, Commented Aug 9, 2017 at 6:02

jezrael · Accepted Answer · 2017-08-09 06:01:28Z

1

You need | for or:

otherdf =  mydf.loc[(mydf['month'] != 2) | (mydf['day'] != 29) ]

What is same as:

otherdf =  mydf.loc[~((mydf['month'] == 2) & (mydf['day'] == 29)) ]
print (otherdf)
   day  month
1   24      3
2   20      7
3   29      8

answered Aug 9, 2017 at 6:01

jezrael

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