measureme | Support crate for rustc 's self-profiling feature | DevOps library

I have a 2 large dataframes containing various variables, I need to add variable distance_from_capital_city, that would be defined as folows:

One dataframe has all country names and capital cities and their coordinances (cap_coordinances in exaple below) and I have another dataframe that has some variables in same countries sometimes in capital city sometimes not.

I need to add variable distance_from_capital_city to real_data dataframe (in example below) and the result should look like this:

First 4 rows of variable distance_from_capital_city in dataframe real_data should be equal to zero (or some small number because coordinances do not have to match exactly and rounding error etc.) and last fifth row should contain distance from Barcelona to Matrid (grouped_by country). Distance should be measured in kilometrs from capital city, or any euclidian distance or any other suitable measuremeent.

Using for example this funtion: