[R] question: how to select a column from a dataframe in a function

[R. Michael Weylandt]

Just put the columnname variable into the brackets as well: they
accept strings.

As a general rule, always use the brackets (single or double) when
programming: `$` has some great features for interactive use but can
bite if you're not careful.

Michael

On Fri, Jan 13, 2012 at 5:34 PM, Julia Burggraaf <jmburggraaf at gmail.com> wrote:
> Hi,
>
> I am creating a function and ran into the problem of selecting a column
> from a dataset. It seems as though the $ function (as in data$columnname)
> does not apply in the function. In simplified version:
>
> This works:
>  testf2<-function(data,columnnumber){print(data[,columnnumber])}
>
> But this doesn't:
> testf<-function(data,column){print(data$column)}
>
> Even though the first solution works, I would like to be able to insert the
> columnname in the function, instead of the columnnumber. How do I do that?
>
> Thank you in advance,
>
> Julia
>
>        [[alternative HTML version deleted]]
>
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