Pre-processing to remove non-numeric columns

[mpadge]

I've started playing around with this package for my own work, for which it's looking really promising. Also opens up a very interesting "can-o-worms" regarding justification of which ordination method one chooses 😟 ... but that discussion can be held some other time and place. In the meantime, as a first observation:

It would be useful to have a couple of pre-processing steps to make the package more "user friendly." One would be to do a simple check for any non-numeric columns and reduce the input object, xx, down to numeric columns only. This is done in most stats routines including cmdscale, prcomp, and the like, which just issue warnings yet still process the data. dobin currently errors with very uninformative message, Error in max.z - min.z : non-numeric argument.

[sevvandi]

Thanks Mark. I've done the pre-processing to remove non-numeric values. I also added a non-normalising option.