Pandas: filling missing values by mean in each group

Question

This should be straightforward, but the closest thing I\'ve found is this post: pandas: Filling missing values within a group, and I still can\'t solve my problem....

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Answer 1

df.fillna(df.groupby(['name'], as_index=False).mean(), inplace=True)

Answer 2

You can also use "dataframe or table_name".apply(lambda x: x.fillna(x.mean())).

Answer 3

I'd do it this way

df.loc[df.value.isnull(), 'value'] = df.groupby('group').value.transform('mean')