Here is another way of doing it:
> x <- read.table(text = " Count Volume FCLASS
+ 1 55000 60000 'Grade Separated'
+ 2 43000 39000 'Grade Separated'
+ 3 26000 26500 'Major Arterial'
+ 4 19500 20000 'Major Arterial'", as.is = TRUE)
> result <- sapply(split(x, x$FCLASS), function(.grp) cor(.grp$Count,
.grp$Volume))
>
> result
Grade Separated Major Arterial
1 1
>
On Thu, Mar 1, 2012 at 12:23 PM, Walter Anderson <wandrso...@gmail.com>wrote:
> I have a data frame with a number of observed and predicted values by
> classification as shown below:
>
> Count Volume FCLASS
> 1 55000 60000 Grade Separated
> 2 43000 39000 Grade Separated
> 3 26000 26500 Major Arterial
> 4 19500 20000 Major Arterial
> ...
>
> There are four classes here: Grade Separated, Major Arterial, Minor
> Arterial, and Collector
>
> I am looking to compute the following information
>
> FCLASS cor(Count,Volume)
> Grade Separated 0.999
> Major Arterial 0.999
> Minor Arterial 0.999
> Collector 0.999
>
> I am attempting to use the following commands to achieve this:
>
> library(reshape)
> tmp <- melt(dataframe)
> cast(tmp, FCLASS ~ variable, function(Count, Volume) cor(Count, Volume))
>
> but this is generating: Error in is.data.frame(y) : argument "Volume" is
> missing, with no default
>
> Any suggestions?
>
> Walter Anderson
>
> ______________________________**________________
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> PLEASE do read the posting guide http://www.R-project.org/**
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> and provide commented, minimal, self-contained, reproducible code.
>
--
Jim Holtman
Data Munger Guru
What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.
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