Change value in one dataframe if it matches in another dataframe

Question

I have created 2 Pandas DataFrame

DataFrame1.Number contains wrong values but DataFrame2.Number contains right values.

I want to replace value of DataFrame1.Number to values in DataFrame2.Number if all the columns values gets matched, i.e.

DataFrame2.Name == DataFrame1.Name and
DataFrame2.Value1 == DataFrame1.Value1 and
DataFrame2.Value2 == DataFrame1.Value2 and
DataFrame2.Value3 == DataFrame1.Value3 and
DataFrame2.Value4 == DataFrame1.Value4

Expected Result in DataFrame1: DataFrame1 Expected Result Image

I am unable to achieve required result. Please Help!!!

Can you try and post your data in a [reproducible](https://stackoverflow.com/questions/52413246/how-to-provide-a-reproducible-copy-of-your-dataframe-with-to-clipboard) format please? No one will spend time recreating your datasets from scratch. — sophocles, Apr 02 '21 at 10:15

score 0 · Answer 1 · answered Apr 02 '21 at 10:18

0

df3=pd.merge(d1,df2, how='left', on='Name')

Also please review pd.merge

answered Apr 02 '21 at 10:18

Eren Han

321
3
10

Hi, Eren Han. Thanks for the reply but this would create a dataframe of shape (37, 11). This is not I wanted. – Dhaval Amodwala Apr 02 '21 at 10:29
hey did you try df=df3[['column1','column2',....]] ? – Eren Han Apr 02 '21 at 10:32

score 0 · Accepted Answer · answered Apr 02 '21 at 10:34

Use pandas.DataFrame.merge() to merge on Name, Value1, Value2, Value3 and Value4 columns, then use pandas.DataFrame.update() to update df1 Number column according to the merged Number_y column which is from the df2 dataframe.

df1["Number"].update(df1.merge(df2, on=["Name", "Value1", "Value2", "Value3", "Value4"], how="outer")["Number_y"])

Change value in one dataframe if it matches in another dataframe

2 Answers2