How to get average salary for each experience level for each job title?

[akshdfyehd]

Hi, I got the dataset like following:

I would like to get average salary for each experience level in each job title, I have tried:

 second=combine(groupby(new,:experience_level,),:salary_in_usd =>IMD.mean)

but then I realized if I do the leftjoin here it will be same salary for all experience level in different job title, my goal is to get a dataset where each experience level have average salary in each job title,does anyone knows how to do that?
Thanks

[nilshg]

Please cross reference questions when posting to multiple sites - this was answered on stackoverflow already.