Fix off-by-one error

This sounds like a really cool project.  I did find a small bug though.

A more sensible language would have noticed that you were creating something 23 columns wide out of a set of 22 columns and thrown a warning or error.

But R cheerfully fills in the extra column with a replica of `bio1` at the end of the data frame. Because what if that's what you actually wanted to do? :unamused:

My patch should be less susceptible to these sorts of problems.