replace nan values by mean group by date.year, date.month

[AnkitGupta]

I want to replace NAN value of Product_price column using fillna Mean based on product ID how I can implement. Is it possible I cant implement for all columns in my dataset based on Product_id

data['product_id'] = data.groupby('product_id').product_price.transform(lambda x: x.fillna(x.mean()))