r- how to edit elements on x axis in image.plot -

i have created image plot data:

sample          p         p.1         p.2         p.3         p.4   p    1.0000000  0.24077171 -0.66666667 -0.49009803  0.61237244   p.1  0.2407717  1.00000000  0.09028939 -0.83444087  0.14744196   p.2 -0.6666667  0.09028939  1.00000000  0.21004201  0.10206207   p.3 -0.4900980 -0.83444087  0.21004201  1.00000000 -0.08574929   p.4  0.6123724  0.14744196  0.10206207 -0.08574929  1.00000000 

using code:

  image.plot(sample,col=redblue(191), zlim=c(-1,1)) 

i image:

instead of 0.0 0.2 0.4.. on x , y axes, want p p.1 p.2... how that? thank time , consideration?

my heatmap looks this:

its not symmetric. can please fix this? using code:

shades=c(seq(-1,-0.5,length=64), seq(-0.5,0.5, length=64), seq(0.5,1,length=64))
heatmap.2(sample, dendrogram='none', symm=true, rowv=false, colv=false, key=true, cexcol=0.7, cexrow=1,scale="row", keysize=1, col=redblue(191), breaks=shades)

here better-ish solution:

 par(mar=c(5,4.5,4,7))  image(sample, col=rainbow(25), axes=f)  #redblue() doesn't work on computer.  axis(2)  axis(1, at=seq(0,0.8,0.2), labels=rownames(sample))  image.plot(sample, legend.only=t) 

edit: plot below looking for?

 sample = cor(matrix(rnorm(400), nrow=20))  image(cor(matrix(rnorm(400), nrow=20)), axes=f)  mtext(text=c(paste("country",1:21)), side=2, line=0.3, at=seq(0,1,0.05), las=1, cex=0.8)  mtext(text=c(paste("country",1:21)), side=1, line=0.3, at=seq(0,1,0.05), las=2, cex=0.8)  image.plot(sample, legend.only=t)