Le jeudi 05 janvier 2012 à 16:51 +0100, Christof Kluß a écrit :
> Hi
>
> I want to do something like
>
> a <- c(10,20,15,43,76,41,25,46)
> tab <- data.frame(a)
>
> name <- "a"
>
> for (v in unique(tab[[name]])) {
> r <- subset(tab, name==v) # this does not work
> ...
> }
>
> i.e. a "string" on the left side of the select expression (subset). How
> could I solve this?
>
> the output should look like r <- subset(tab, a==v)
> but now I have something like r <- subset(tab, "a"==v)
> and r <- subset(tab, [["a"]]==v)
> does not work :(
Not sure what you want to do. The subset() commands you're using will
select the rows from tab that match the given expression, which in your
first example is "name==v". The problem is, none of the values of tab is
equal to "a" (the value of 'name'), so it returns nothing. You can check
it by just typing:
name==v
So, please tell us what you want to achieve, rather than how you're
doing it (wrong). ;-)
Cheers
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