R help - Jan 2012 - Using Aggregate() with FUN arguments, which require more than one input variables

Dear all,

I am trying to apply the aggregate() function to calculate correlations for
subsets of a dataframe. My argument x is supposed to consist of 2 numerical
vectors, which represent x and y for the cor() function. 

The following error results when calling the aggregate function: Error in
FUN(X[[1L]], ...) : supply both 'x' and 'y' or a matrix-like
'x'. I think
the subsets aggregate puts into cor() are sort of list types and therefore
can't be handled by cor().

Can anyone provide me with a solution?

Regards,
RNoob

--
View this message in context:
http://r.789695.n4.nabble.com/Using-Aggregate-with-FUN-arguments-which-require-more-than-one-input-variables-tp4303936p4303936.html
Sent from the R help mailing list archive at Nabble.com.

On 17.01.2012 18:10, RNoob wrote:
> Dear all,
>
> I am trying to apply the aggregate() function to calculate correlations for
> subsets of a dataframe. My argument x is supposed to consist of 2 numerical
> vectors, which represent x and y for the cor() function.
>
> The following error results when calling the aggregate function: Error in
> FUN(X[[1L]], ...) : supply both 'x' and 'y' or a
matrix-like 'x'. I think
> the subsets aggregate puts into cor() are sort of list types and therefore
> can't be handled by cor().

as.matrix() will probably help, but since you have not specified your 
reproducible code, we cannot show how to change that.

Uwe Ligges

> Can anyone provide me with a solution?
>
> Regards,
> RNoob
>
> --
> View this message in context:
http://r.789695.n4.nabble.com/Using-Aggregate-with-FUN-arguments-which-require-more-than-one-input-variables-tp4303936p4303936.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

Hello,


RNoob wrote
> 
> Dear all,
> 
> I am trying to apply the aggregate() function to calculate correlations
> for subsets of a dataframe. My argument x is supposed to consist of 2
> numerical vectors, which represent x and y for the cor() function. 
> 
> The following error results when calling the aggregate function: Error in
> FUN(X[[1L]], ...) : supply both 'x' and 'y' or a
matrix-like 'x'. I think
> the subsets aggregate puts into cor() are sort of list types and therefore
> can't be handled by cor().
> 
> Can anyone provide me with a solution?
> 
> Regards,
> RNoob
> 
I don't know if I'm understanding it well but it seems you're trying
to
compute a correlation matrix for each group of a data.frame. The data.frame
is divided into groups by one or more factor columns.  If this is what you
want, try the function below. It doesn't use 'aggregate', it uses
'split'
and 'lapply'.


cor.groups <- function(x, vars){
	cols <- if(is.character(vars)) names(x) else 1:ncol(x)
	cols <- cols %in% vars
	cols <- cols | sapply(x, is.factor) | sapply(x, is.character)
	# transform logical to numeric index
	cols <- which(cols)

	lapply(split(x, x[, vars]), function(grp) cor(grp[, -cols]))
}

# Sample data
N <- 100
DF <- data.frame(U=as.factor(sample(LETTERS[1:3], N, T)),
			V=as.factor(sample(0:1, N, T)),
			W=sample(letters[1:6], N, T),
			x=1:N, y=sample(10, N, T), z=rnorm(N),
			stringsAsFactors=FALSE)

# And test it. Note the argument 'stringsAsFactors'

cor.groups(DF, "U")
cor.groups(DF, c("U", "V"))
cor.groups(DF, 1:3)
cor.groups(DF, c("U", "x"))     # look out, right result,
wrong function
call


I hope it helps. (if not, be more explicit)

Rui Barradas


--
View this message in context:
http://r.789695.n4.nabble.com/Using-Aggregate-with-FUN-arguments-which-require-more-than-one-input-variables-tp4303936p4304535.html
Sent from the R help mailing list archive at Nabble.com.