python 分组并迭代数据帧，将值分配到列表，然后与原始值合并

Posted 2021-05-08

group = df.groupby('title')
author_counts = group.apply(lambda x: x['author'].nunique()).reset_index().rename(columns={0:'author_count'})

df_five= author_counts[author_counts.author_count<=5]

df_five['authors'] = [list(set(df['author'].loc[df['title'] == x['title']])) 
    for _, x in df_five.iterrows()]
    

df_copy = df.copy()
del df_copy['author']
df_copy.drop_duplicates(keep='first',inplace=True)
merge =df_five.merge(df_copy, on='title', how='left')