Need help mutating columns

Hi, welcome to the forum.

At the very least, we are going to need some sample data. It looks like you are using latitude and longitude data so we ned to know its format and so on.

A handy way to supply some sample data is the dput() function. In the case of a large dataset something like dput(head(mydata, 100)) should supply the data we need.

More generally we may need a FAQ: How to do a minimal reproducible example ( reprex ) for beginners