How to merge pandas value_counts() to dataframe or use it to subset a dataframe

Question

I used pandas df.value_counts() to find the number of occurrences of particular brands. I want to merge those value counts with the respective brands in the initial dataframe.

Answer 1

i think the best way is to use map

df['brand_count']= df.brand.map(df.brand.value_counts())

this is so much faster than groupby method for example (factor 500 on a 15000 row df) and take only one line