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Just for Fun: Using R to Create Targets

Aug 10, 2010 metroadmin

OK, not really science or soil-related, but a fun 5 minute use of R to make something you can use to improve your hand-eye coordination. Demonstrates several ways to use base graphics, user-defined functions, and calling functions from within other functions.

Implementation

# function to make the target
f.target <- function(xy, s)
        {
        plot(0, 0, type='n', axes=FALSE, xlab='', ylab='', xlim=c(-1,1), ylim=c(-1,1))
        grid(nx=50, ny=50, lty=1)
        abline(h=0, v=0, lwd=2)
        f.bullseye(list(x=0,y=0), s)
        f.bullseye(xy, s/2)    
        }

# function to make each bull's eye
f.bullseye <- function(xy, s)
        {
        sapply(s, function(s_i) {
                points(xy, cex=s_i, lwd=2) } )
        }


# concentric circle sizes
s <- c(2,8,16,24,32)
# coordinates for bull's eye marks in each quadrant
xy <- expand.grid(x=c(-0.66, 0.66), y=c(-0.66, 0.66))

# save 2x2 figure to PDF
pdf(file='target_2x2.pdf', width=11, height=8.5)
par(mfcol=c(2,2), mar=c(1,1,1,1))
for(i in 1:4) f.target(xy, s)
dev.off()

# save 2x1 figure to PDF
pdf(file='target_2x1.pdf', width=8.5, height=11)
par(mfcol=c(2,1), mar=c(1,1,1,1))
for(i in 1:2) f.target(xy, s)
dev.off()