[GenABEL-dev] [Fwd: Re: descriptives.trait Patch]

[pirastu at burlo.trieste.it]

Actually yes, its a trick I've used to eliminate the "". If you use ~ R
will interpeter as a formula and will not require quotes.

You can try to type something like a<-x~y, a will be of class formula.
you can actually make lists with more formulas.

 a<- x~y
 b<-f~d
 c(a,b)

They will be taken by lm and other things.

That said this will work also with ~x for example.
If you do

as.character(a)
[1] "~" "x" "y"

basically I used this to avoid having the error " sex is not an object" or
something like that.
Also from a "formal" point of view it makes sense, in fact when you make a
boxplot for example you would type

boxplot(trait~sex)

to get a boxplot for each category.

I could infact change descriptives.trait to work in the same way,
something like

descriptives.trait(srdta~sex)

which might be a little more intuitive, but this solution was quicker at
least to implement.

Hope to have answered your questions.

Best

Nicola



>> 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
>