Converting NaN in dataframe to zero

Question

I have dictionary and created Pandas using cars = pd.DataFrame.from_dict(cars_dict, orient='index') and sorted the index (columns in alphabetical order
cars = cars.sort_index(axis=1) After sorting I noticed the DataFrame has NaN and I wasn't sure if the really np.nan values? print(cars.isnull().any()) and all column shows false.

I have tried different method to convert those "NaN" values to zero which is what I want to do but non of them is working. I have tried replace and fillna methods and nothing works Below is sample of my dataframe..

            speedtest          size 
toyota       65                NaN 
honda        77                800

I just went for the df.replace('NaN', 0) that worked fine. thanks. — Josef
– Josef, Commented Feb 23, 2018 at 22:07

Tiago Peres · Accepted Answer · 2020-06-14 08:41:37Z

32

Either use replace or np.where on the values if they are strings:

df = df.replace('NaN', 0)

Or,

df[:] = np.where(df.eq('NaN'), 0, df)

Or, if they're actually NaNs (which, it seems is unlikely), then use fillna:

df.fillna(0, inplace=True)

Or, to handle both situations at the same time, use apply + pd.to_numeric (slightly slower but guaranteed to work in any case):

df = df.apply(pd.to_numeric, errors='coerce').fillna(0, downcast='infer')

Thanks to piRSquared for this one!

edited Jun 14, 2020 at 8:41

Tiago Peres

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answered Feb 23, 2018 at 22:04

cs95

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1 Comment

piRSquared Over a year ago

Generalized: df.apply(to_numeric, errors='coerce').fillna(0, downcast='infer')

Gonçalo Peres · Accepted Answer · 2020-06-14 09:08:27Z

3

@cs95's answer didn't work here.

Had to import numpy as np and use replace with np.Nan and inplace = True

import numpy as np

df.replace(np.NaN, 0, inplace=True)

Then all the columns got 0 instead of NaN.

answered Jun 14, 2020 at 9:08

Gonçalo Peres

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Comments

L Tyrone · Accepted Answer · 2024-06-11 23:24:41Z

1

Don't use inplace=True and try this instead:

df.fillna(0)

edited Jun 11, 2024 at 23:24

L Tyrone

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answered Jun 11, 2024 at 17:29

Ali Seify

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