plot data from tapply

i have three data, x coordinate, y coordinate and  signal strength

i use tapply() function to get the average ss in the give x,y location
 x=c(1,2,3,1)
 y=c(1,2,3,1)
 ss=c(55,NA,55,88)
  ss_byxy_test=tapply(  ss, list( x, y), mean)
and I get this table
     1  2  3
1 71.5 NA NA
2   NA NA NA
3   NA NA 55
but i don't know how to plot different the ss with the xy location,
can anyone help me

View this message in context: http://n4.nabble.com/plot-data-from-tapply-tp949436p949436.html
Sent from the R help mailing list archive at Nabble.com.