[R] duplicate data points on a line graph

Carl Witthoft carl at witthoft.com
Thu Jul 16 03:56:00 CEST 2009


If you want to take the second  approach, it can be relatively easily 
generalized by calculating the cex values based on the count of ordered 
pairs in the original dataset.

Here's a data set:
 > xy
      x y
[1,] 1 4
[2,] 1 5
[3,] 2 3
[4,] 3 3
[5,] 4 5
[6,] 5 2
[7,] 1 4
[8,] 2 3

Here's the same set fully sorted:

xy[order(x,y),]->xyord
      x y
[1,] 1 4
[2,] 1 4
[3,] 1 5
[4,] 2 3
[5,] 2 3
[6,] 3 3
[7,] 4 5
[8,] 5 2

There's gotta be some very simple way to create a series of values for 
cex but I'm missing it, other than a loop like

cexvec<-rep(1,8)
for i in 2:8 {
if (xyord[i,1]==xyord[i-1,1] & xyord[i,2]== xyord[i-1,2] ) {

cexvec[i]<-cexvec[i-1]+1
}
}

You get the idea, sort of  :-)

Carl


On 7/15/2009 2:19 PM, NDC/jshipman wrote:
 > Hi,
 >     I am new to R plot.  I am trying to increase the data point
 > observation when duplicate data points exist
 >
 > x    y
 > 1    10
 > 1    10
 > 2    3
 > 4    5
 > 9     8
 >
 >
 > in the about example  1, 10 would be displayed larger than the other
 > data points.  Could someone give me some assistance with this problem

   A couple of simple approaches:

x <- c(1,1,2,4,9)

y <- c(10,10,3,5,8)

plot(jitter(x), jitter(y))

plot(x, y, cex=c(2,2,1,1,1))

 > 757-864-7114
 > LARC/J.L.Shipman/jshipman
 > Jeffery.L.Shipman at nasa.gov




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