'Assign pandas dataframe column value based on first ocurrence

I have a dataframe df1 :-

I want to achieve this transformation in df1:-

Wherever chcolate has ocurrence count>1 ,Based on first ocurrence assign the brand the same value

python pandas

Solution 1:^[1]

something like this should work where we groupby chcolate and replace the brand with the first element from that group

df['brand'] = df.groupby('chcolate')['brand'].transform(lambda r:r.iloc[0])

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Solution	Source
Solution 1	piterbarg