itertuples, new column, datetime, pandas

[karlito]

I thought you asked because you wanted to help? :)

Did you provide sample data in easy to use (copy-paste) format?

Did you provided enough information ('Date as index' - is it datetime.date or what?, do you want select or sum all values less than 20?, are all errors and typos in sample eliminated?).

If one makes helping as hard as possible then it significantly reduces possibilities that someone is ready to invest time and effort into it.

Oh sorry about that! I will modify the original post and then add additional infos.