[Python] Replacing values with groupby means

I have a DataFrame with a column that has some bad data with various negative values. I would like to replace values < 0 with the mean of the group that they are in.

For missing values as NAs, I would do:

data = df.groupby(['GroupID']).column
data.transform(lambda x: x.fillna(x.mean()))


But how to do this operation on a condition like x < 0?

Thanks!

Continue reading...