R help - Jan 2004 - Returning data in matrix form

I am trying to perform the following calculation for a very
large time series data set:

x<-unit(length*data.frame.a*data.frame.b,"cm")

data.frame.a and data.frame.b are of the same dimension, and I wish to
perform the calculation in one step so that "x" is returned as a
matrix/data.frame of equal dimension.

I have tried a couple of methods for this, (subsetting data.frame.a and
data.frame.b and performing the calculation on a column by column basis
for instance, and trying to loop a function over column data), but each
time I am returned with a list for x rather than a data frame.

Sorry if this is a stupid question, I have looked through some R
literature but don't seem able to find the answer.

Thank you for any help.

Laura

On 01/19/04 19:27, Laura Quinn wrote:
>I am trying to perform the following calculation for a very
>large time series data set:
>
>x<-unit(length*data.frame.a*data.frame.b,"cm")
>
>data.frame.a and data.frame.b are of the same dimension, and I wish to
>perform the calculation in one step so that "x" is returned as a
>matrix/data.frame of equal dimension.
Sounds like mapply() would be useful.  It works on columns of
data frames.  The default is "simplify=TRUE" so it will try to
return a vector or matrix.

Jon
--
Jonathan Baron, Professor of Psychology, University of Pennsylvania
Home page:            http://www.sas.upenn.edu/~baron
R page:               http://finzi.psych.upenn.edu/