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I am working on Jupyter, I have a large dataset which contains missing values. I have replaced the question mark to NaN, but when I am counting the missing values in the dataset, the command is not executing as it returns 0 value.. I have tried this command, but not succeed: 

print(com.isnull().sum())

Replaced question mark by NaN:

Returning 0 value:

Omar Einea
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Jack
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  • The problem is actually with `replace`. If you print your dataframe after it, you will see that it didn't work. See [here](https://stackoverflow.com/questions/37593550/pandas-replacing-elements-not-working) for explanation – Georgy Mar 04 '18 at 16:16

1 Answers1

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By default, replace does not modify the dataframe in-place. Instead, it returns a dataframe with the modifications made.


Just change the relevant line of code to:

com.replace('?', np.NaN, inplace=True)
nisemonoxide
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