[R] subset bug?
Mike Saunders
mike_saunders at umenfa.maine.edu
Fri Dec 10 18:39:43 CET 2004
Bert:
Thanks for your reply. Actually, "mat" was a data.frame, not a matrix.
Mike
----- Original Message -----
From: "Berton Gunter" <gunter.berton at gene.com>
To: "'Mike Saunders'" <mike_saunders at umenfa.maine.edu>; "'R Help'"
<r-help at stat.math.ethz.ch>
Sent: Friday, December 10, 2004 11:57 AM
Subject: RE: [R] subset bug?
> 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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