Add a legend of colors in image {graphics}

问题

In this example, I have an image with colors and I wonder if we can add a legend of colors. for example : points with z in [8:10] have color red and so on.

x=runif(500,0,5)
y=runif(500,0,5)
z=floor(runif(500, 1,10)) 
xyz=data.frame(x,y,z)
library(MBA)
mba.int <- mba.surf(xyz, 300, 300, extend=T)$xyz.est
image(mba.int, xaxs="i", yaxs="i")

Thank you.

回答1:

Thanks to @user20650, the answer is :

fields::image.plot(mba.int, col = heat.colors(12))

回答2:

Something along the lines. Expand the logic and numbers to suit your needs.

col1 = ifelse(z < 4 , "red", ifelse(z >=4 , "green", "black")) 
image(mba.int, xaxs="i", yaxs="i", col= col1)

来源：https://stackoverflow.com/questions/28301514/add-a-legend-of-colors-in-image-graphics