[R] subset bug?

[Berton Gunter]

The subset() Help file says

"The select argument exists only for the method for data frames ..."

So if mat is a matrix and not a data.frame, this might be the source of your
problems.

-- Bert Gunter
Genentech Non-Clinical Statistics
South San Francisco, CA
 
"The business of the statistician is to catalyze the scientific learning
process."  - George E. P. Box
 
 

> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Mike Saunders
> Sent: Friday, December 10, 2004 5:02 AM
> To: R Help
> Subject: [R] subset bug?
> 
> I ran into a problem with "subset" while working at home that 
> I am not sure is a bug or not.  I defined a custom function 
> to take a data frame of tree positions, sizes, and types 
> (containing the columns TRT, COMP, PLOT, X, Y, DBH and CON) 
> and wanted to make a stem map of the plot using different 
> symbols and colors to represent the different types of tree 
> stems.  I copied a bit of the code below, the part that gave 
> me troubles:
> 
> if(dim(subset(mat,CON==1 & DBH>11.43))[1]>0) 
> symbols(mat[mat$CON==1 &     mat$DBH>11.43,]$X,mat[mat$CON==1 
> & mat$DBH>11.43,]$Y,circles=log(mat[mat$CON==1 & 
> mat$DBH>11.43,]$DBH)*tuner,inches=FALSE,add=TRUE,fg="gray",lwd=2)
> 
> if(dim(subset(mat,CON==0 & DBH>11.43))[1]>0) 
> symbols(mat[mat$CON==0 & mat$DBH>11.43,]$X,mat[mat$CON==0 & 
> mat$DBH>11.43,]$Y,squares=log(mat[mat$CON==0 & 
> mat$DBH>11.43,]$DBH)*sqrt(pi)*tuner,inches=FALSE,add=TRUE,fg="
> gray",lwd=2)
> 
> if(dim(subset(mat,CON==1 & DBH<=11.43))[1]>0) 
> symbols(mat[mat$CON==1 & mat$DBH<=11.43,]$X,mat[mat$CON==1 & 
> mat$DBH<=11.43,]$Y,circles=log(mat[mat$CON==1 & 
> mat$DBH<=11.43,]$DBH)*tuner,inches=FALSE,add=TRUE,fg="black",lwd=2)
> 
> if(dim(subset(mat,CON==0 & DBH<=11.43))[1]>0) 
> symbols(mat[mat$CON==0 & mat$DBH<=11.43,]$X,mat[mat$CON==0 & 
> mat$DBH<=11.43,]$Y,squares=log(mat[mat$CON==0 & 
> mat$DBH<=11.43,]$DBH)*sqrt(pi)*tuner,inches=FALSE,add=TRUE,fg=
> "black",lwd=2)
> 
>  The item "tuner" just scales the symbol size.  As you can 
> see, I was using two columns to define the type of symbol 
> (CON: square vs. circle) and color (DBH: gray vs. black).  I 
> had to use the "if" statements because some of the plots did 
> not contain all combinations of tree types.  This worked fine 
> in giving me my plots.
> 
> Okay, the question I had was why I couldn't use the "subset" 
> function within the "symbols" command.  I was going to use:
> 
> subset(mat,CON==0 & DBH<=11.43,select=c(X,Y))
> 
> as the first entry into the symbols command, but it kept 
> giving me errors saying "xy.coords" could not convert it.  
> However, if I used the "plot" function with "subset" trimming 
> the data frame externally, it worked fine to plot the point 
> positions.  However, the help for "plot" and "plot.default" 
> says "xy.coords" is used within that function.  What am I 
> missing here?
> 
> Mike Saunders
> Research Assistant
> University of Maine
>  
> 	[[alternative HTML version deleted]]
> 
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