[GenABEL-dev] descriptives.trait Patch

[Yurii Aulchenko]

> I was looking at the documentation changes you made, and I just wanted to
> point out that another version of the command is:
>
> descriptives.trait(srdta, by.var=~sex)
>
> whithout "".

I have noticed that type of passing an argument in your test-code, but
thought of dropping this as I have no idea what this means. Looking
for help("~") returned explanation for "~" as a part of formula.

Do you know what this actually means and how it works?

Yurii