[R] Identifying points in a plot that have duplicate values

[Jim Lemon]

David Lloyd wrote:
> I have code like this: - 
> 
> #-----------------------------------------------------------------------
> ------------------------------------------------------
> 
> x=scan()
> 0 0 0 0 0 1 2 3 4
> 
> y=scan()
> 1 1 1 2 2 1 3 4 5
> 
> plot(x,y)
> 
> identify(0,1,3) #Allows me to select manually to identify co-ordinate
> (0,1) as being duplicated 3 times
> identify(0,2,2) #Allows me to select manually to identify co-ordinate
> (0,2) as being duplicated 2 times
> #-----------------------------------------------------------------------
> ------------------------------------------------------
> 
> Is there not a way I can automatically display if points are duplicated
> and by how many times?
> 
> I thought if I 'jittered' the points ever so slightly I could get an
> idea of how many duplicates there are but with >100 points the graph
> looks very messy.
> 
Hi David.
In the plotrix package there are a few functions that might be helpful.

cluster.overplot - moves ovelying points into a small cluster up to 9
count.overplot - displays the number of overlying points
sizeplot - displays symbols with size relative to the number of points

Jim