有選擇地從另一個 dataframe 替換 dataframe 中的值

Question

我有兩個數據框：

df1

   Company Name     Symbol     ID
0       AAA Inc  No Symbol    123
1       BBB Inc          B    456
2       CCC Inc          C    789
3       DDD Inc          D    112
4       EEE Inc          E    134
5       FFF Inc  No Symbol    156

df2

   Company Name     Symbol     ID
0       Aaa Inc          A    123
1       bbb Inc          B    456
2         C  Co  No Symbol    789
3       fff Inc          F    156
4       ZZZ Inc          Z    999

我想通過使用ID作為查找，只用df2中的符號替換df1中的No Symbol Symbol ，這樣 output 看起來像這樣：

   Company Name     Symbol     ID
0       AAA Inc          A    123
1       BBB Inc          B    456
2       CCC Inc          C    789
3       DDD Inc          D    112
4       EEE Inc          E    134
5       FFF Inc          F    156

我如何實現這一目標？

Answer 1

df1_no_symbol_id = df1[df1['Symbol']=='No Symbol']['ID']

df2_symbol_id_values_list = df2[df2['ID'].isin(df1_no_symbol_id)].to_dict('records')

for i in df2_symbol_id_values_list:
    id = i['ID']
    value = i['Symbol']
    df1.loc[df1.ID==id, 'Symbol'] = value