如何将列的空白从一个数据框填充到另一个数据框？

Question

i have a 2 dataframe, i wanted to fill the ID column blank with help first column ID. The data is not Identical the second data is having less number of entry. And I have to find the id values with respect to the C_name column. If C_Name and I'd of 1st data is equal to the 2rd data value the value from 1 data should come to 2 data frame

C_Name  ID  item ID
Ad  ADV01   ADV001
NC  899 NC01
NC  899 NC01
Med 14996   0-A
Bank    20668   BNK002
Light   LIG01   LIG01
Light   LIG01   LIG03
Light   LIG01   LIG03
Light   LIG01   LIG03
Ad  ADV01   AD01
Ivar's  IVARS01 I01
Ad  ADV01   AD01
Light   LIG01   LIG03
OneNet  ONT01   ONENET001
Light   LIG01   LIG03
Tri CAL01   201-TP
Tri CAL01   201-SPK
Tri CAL01   201-CHI
Light   LIG01   2059
Light   LIG01   2059
Light   LIG01   2059
Light   LIG01   2059
Light   LIG01   2059
Distribution    DMSI01  2052

second data

C_Name  ID  item ID
Ad  ADV01   ADV001
NC  899 NC01
NC      NC01
Med 14996   0-A
Bank    20668   BNK002
Light   LIG01   LIG01
Light       LIG03
Light       LIG03
Light       LIG03
Ad  ADV01   AD01
Ivar's  IVARS01 I01
Ad  ADV01   AD01
Light   LIG01   LIG03
OneNet  ONT01   ONENET001
Light   LIG01   LIG03
Tri CAL01   201-TP
Tri     201-SPK
Tri     201-CHI
Light   LIG01   2059
Light       2059
Light       2059
Light       2059
Light       2059
Distribution    DMSI01  2052

how should i do it?

Answer 1

You can use series.update(other) as

df2.ID.upadte(df1.ID)

Careful with

1. Pandas aligns the indexes of both series, so if there is not a significant index defined it wil work with the default RangeIndex. If this is the case and dfs don't the same amount of rows in the same order then you will get unexpected results.
2. All non-NA values from df1 will be copied to df2, if df2 already had a value it will be overwritten