如何在 python 数据框中执行以下操作

Question

below are my two dfs

df = pd.DataFrame(np.random.randint(1,10,(5,3)),columns=['a','b','c'])
dd = pd.DataFrame(np.repeat(3,2),columns=['a'])

I want to replace the column 'a' of df with values in column 'a' of dd. Any empty rows are replaced by zero "only" for column 'a'. All other columns of df remain unchanged.

so column 'a' should contain 3,3,0,0,0

Answer 1

This is probably not the cleanest way, but it works.

    df['a'] = dd['a']
    df['a'] = df['a'].fillna(0)