[R] Question of programming style

s-luppescu@uchicago.edu s-luppescu at uchicago.edu
Sat Jul 8 00:56:10 CEST 2000

This is really a question of how to program this *BETTER*. It works as I have
done it, but is quite ugly. 

I want to do a 3d scatterplot of the upper triangle of a matrix, where the
z-values are the values in the matrix, and the row and column indices are the y-
and x-values. The complete (11 by 11) matrix is mmtop94.2. Here is my awkward

mmtop94.2[lower.tri(mmtop94.2)] <- NA

# Here i is the row (y variable), j is the column (x var)
plotdata <- matrix(0, ncol=3, nrow=121)
for (i in 1:11)
    for (j  in 1:11)
        k <- (i-1) * 11 + j
        plotdata[k,] <- c(j, abs(i - 12), mmtop94.2[i, j])
plotdata2 <- na.omit(plotdata)

scatterplot3d(plotdata2, type='h')

It seems to me that I should not have to initialize the plotdata matrix. And
are all those for loops really necessary? 

Thanks in advance for the help.
Stuart Luppescu         -=-=-  University of Chicago
$(B:MJ8$HCRF`H~$NIc(B        -=-=-  s-luppescu at uchicago.edu
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>> Sent on 07-Jul-2000 at 17:45:09 with xfmail
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