how to merge two dataframes and sum the values of columns
I think need set_index for both DataFrames, add and last reset_index:
df = df1.set_index('Name').add(df2.set_index('Name'), fill_value=0).reset_index()print (df) Name class value0 Ram 2.0 8.01 Sri 2.0 10.02 viv 7.0 8.0If values in Name are not unique use groupby and aggregate sum:
df = df1.groupby('Name').sum().add(df2.groupby('Name').sum(), fill_value=0).reset_index()