Merging two pandas dataframes I have two csv files,and if I do:

df_compiler = pd.read_csv('sub_compiler.csv')


I obtain:



and for the other csv file I do:

df_opt = pd.read_csv('sub_opt.csv')


I obtain:



now what I would like to do is merge these two csv files and obtain something like:



can somebody please help me doing this? Thank's in advance.
I would normally suggest something like 

merged_df = pd.merge(df_compiler, df_opt, on="instructions")


But the third image you posted does not really look like the inner merge of the other two. Can you describe what exactly you are trying to achieve in a little more detail? The third one looks like ten times longer than the other two.