Overwrite columns in DataFrames of different sizes pandas

Question

I have following two Data Frames:

df1 = pd.DataFrame({\'ids\':[1,2,3,4,5],\'cost\':[0,0,1,1,0]})
df2 = pd.DataFrame({\'ids\':[1,5],\'cost\':[1,4]})
         


        

Answer 1

You can use set_index and combine first to give precedence to values in df2

df_result = df2.set_index('ids').combine_first(df1.set_index('ids'))
df_result.reset_index()

You get

   ids  cost
0   1   1
1   2   0
2   3   1
3   4   1
4   5   4