search for: ss_melt

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 --