Re: [R] how to get colnames of a dataframe within a function called by 'apply'

From: Gabor Grothendieck <ggrothendieck_at_gmail.com>
Date: Sat 29 Oct 2005 - 12:25:23 EST

Iterate over the column names rather than the columns themselves:

par.or <- par(mfrow=c(3,3))

nv <- function(name, data) {
	qqnorm(data[,name], main=name)
	qqline(data[,name], col="red")
	invisible()

}
sapply(colnames(temp), nv, data = temp)
par(par.or)

On 10/28/05, Leo Gürtler <leog@anicca-vijja.de> wrote:
> Hello alltogether,
>
> how is it possible to assign the colnames of a data.frame to a function
> called by apply, e.g. for labeling a plot?
> Example: I want to plot several qqnorm-plots side by side and there
> should be a maintitle for each qqnorm-plot which is identical to the
> respective colname.
> I checked, but the column which is processed by the function called by
> apply does not contain a colname (because by using str() it seems it is
> no column at this point, but just a e.g. numerical vector).
> I also tried with colnames() from within the function, but was not
> successful to get the apropriate colname - either the whole string or
> just the first one.Thus it lacks of a counter that contains the number
> of the row which is processed.
>
> Here is an example code:
>
> <---snip--->
>
> nv <- function(xno.na)
> {
> par.or <- par(mfrow=c(3,3))
> qqnorm(xno.na, main="HERE SHOULD BE THE NAME OF THE COLUMN")
> qqline(xno.na, col="red")
> par(par.or)
> print(str(xno.na))
> }
>
> > temp # just a part of the whole data.frame
> klarb1 klarb2 abarb laut skla1 skla2
> a NA 13.068182 7.5 4 0.5 0.5
> b NA 6.818182 9.0 6 NA 0.5
> c 15.11628 6.818182 10.0 4 1.0 1.5
> d NA 18.181818 19.0 2 1.0 0.5
>
> > apply(temp,2,nv)
>
> </---snip--->
>
>
> Thanks a lot!
>
> best wishes,
>
> leo
>
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R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Sat Oct 29 12:34:29 2005

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