Converting a Number Matrix to a Color Matrix in R

Question

I have the following 4x4 number matrix containing the numbers 0-4:

0  1  0  3
3  2  1  4
4  1  0  2
3  3  0  1

I would like to understand how to convert number matrices into a color matrices using chosen colors and specific square dimensions (length x width) using R. To be clear, I'm defining color matrix as a figure using colored squares to represent specific values in a matrix orientation. An example 4x4 from another program follows:

I would have to assign color codes to the numbers, for example:

0 = FFFFFF
1 = 99FF66
2 = 66FF33
3 = 33CC00
4 = 009900

But I don't know where to begin putting this together. I imagine I would also have to specify dimensions for color squares as well.

My goal is to be able to import a data frame into R with up to 10 numerical values and create these color charts for matrices as large as 20x20.

Answer 1

Here's what I would do:

d<-read.table(text="
0  1  0  3
3  2  1  4
4  1  0  2
3  3  0  1")

cols <- c(
'0' = "#FFFFFF",
'1' = "#99FF66",
'2' = "#66FF33",
'3' = "#33CC00",
'4' = "#009900"
)
# the names aren't necessary here.

image(1:nrow(d), 1:ncol(d), as.matrix(d), col=cols)

If you'd prefer for the orientation to be different, you can rotate the matrix:

image(1:nrow(d), 1:ncol(d), t(apply(d, 2, rev)), col=cols)

To get rid of all the text and borders, you might try:

image(1:nrow(d), 1:ncol(d), as.matrix(d), col=cols, 
  xaxt="n", yaxt="n", bty="n", xlab="", ylab="")