pandas Python Series objects are mutable, thus they cannot be hashed in query method

Question

I'm tring to run:

import pandas as pd
df_data = pd.DataFrame({'a':[1,20,None,40,50]})
df_data.query('a.isnull()')

and an error happens :

TypeError: 'Series' objects are mutable, thus they cannot be hashed

but:

df_data.a.isnull()

has no error at all, why is this happening? can you help me to figure out why?

rafaelc · Accepted Answer · 2018-08-16 13:43:23Z

12

Use python engine, or use a np.array with the default npexpr engine.

df_data.query('a.isnull()', engine='python')

or

df_data.query('a.isnull().values')

(Not quite sure why numexpr can't handle a pd.Series though)

answered Aug 16, 2018 at 13:43

rafaelc

59.4k15 gold badges64 silver badges87 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

RobotHumans Over a year ago

On why pd.Series might not be able to be handled by insert wherever it used to work, some recent-ish changes that make pandas structs less like numpy dataframes is probably the culprit. Numpy just probably handled it gracefully in the conversion. I've gotten the error before "Error: Object of type <Pandas.Dataframe> is not a Pandas.Dataframe" in the midst of that happening.

BENY · Accepted Answer · 2018-08-16 13:43:50Z

2

You can using !=

df_data.query('a!=a')
Out[10]: 
    a
2 NaN

Since np.NaN not equal to np.NaN

answered Aug 16, 2018 at 13:43

BENY

324k22 gold badges176 silver badges250 bronze badges

1 Comment

Austin Over a year ago

I get ValueError: unknown type object when trying this.

Collectives™ on Stack Overflow

pandas Python Series objects are mutable, thus they cannot be hashed in query method

2 Answers 2

1 Comment

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related