I have 2 dataframes, where I was looking if cells of column player in df1 existed in column last_name of df2. I merged on column player and if it is present in df2 it prints the cell but if its not it prints nan(which is what I wanted). I next wanted to make a description column but only for the non nan values. How can I add description for all the values that aren't nan?

df3 = df.merge(df2, left_on = 'player', right_on = 'last_name', how = 'left')

df1

df2

I changed the matched_player column name for readability with:

df3.rename(columns = {'last_name':'matched_player'}, inplace=True)

output(df3)

expected output

CodePudding user response：

You can try np.where

df3['description'] = np.where(df3['matched_player'].notna(), 'a player from df1', '')
# or
df3['description'] = np.where(df3['matched_player'].isna(), '', 'a player from df1')