Colorize/highlight values of R ftable() output in knitr/Sweave rapports

Question

I am generating a lot of ftable() crosstabulations for a descriptive report. Example:

              AUS  BEL  BUL  EST  FRA  GEO  GER  HUN  ITA  NET  NOR  ROM  RUS

30- primary    0.06 0.03 0.07 0.03 0.02 0.03 0.03 0.02 0.05 0.03 0.05 0.04 0.02
    secondary  0.30 0.09 0.16 0.10 0.10 0.14 0.10 0.16 0.11 0.08 0.08 0.09 0.11 
    tertiary   0.05 0.07 0.04 0.05 0.07 0.06 0.02 0.04 0.02 0.05 0.06 0.02 0.09
30+ primary    0.07 0.16 0.12 0.07 0.16 0.03 0.05 0.11 0.35 0.21 0.09 0.17 0.03
    secondary  0.40 0.20 0.30 0.29 0.25 0.35 0.35 0.34 0.27 0.20 0.27 0.34 0.26
    tertiary   0.13 0.23 0.13 0.18 0.17 0.17 0.18 0.09 0.09 0.23 0.23 0.06 0.24
60+ primary    0.00 0.12 0.10 0.13 0.14 0.07 0.05 0.12 0.09 0.11 0.06 0.19 0.12
    secondary  0.00 0.05 0.05 0.08 0.06 0.10 0.14 0.09 0.02 0.04 0.11 0.07 0.06
    tertiary   0.00 0.05 0.03 0.06 0.03 0.04 0.07 0.03 0.01 0.05 0.06 0.02 0.07

I am looking for a function that could take the ftable() or table() output, and highligh values that deviate from the row-mean, or assign an overall gradient to the text of the values, e.g. from 0-100% the values are coloured from red to green.

The output is now processed through knitr, but I'm not sure at which point in the toolchain I could intervene and add colour based on the relative size of the values.

Answer 1

You can use the latex function, in the Hmisc package.

# Example shamelessly copied from http://www.karlin.mff.cuni.cz/~kulich/vyuka/Rdoc/harrell-R-latex.pdf
cat('
  \\documentclass{article}
  \\usepackage[table]{xcolor}
  \\begin{document}
  <<results=tex>>=
  library(Hmisc)
  d <- head(iris)
  cellTex <- matrix(rep("", nrow(d) * ncol(d)), nrow=nrow(d))
  cellTex[2,2] <- "cellcolor{red}"
  cellTex[2,3] <- "color{red}"
  cellTex[5,1] <- "rowcolor{yellow}"
  latex(d, file = "", cellTexCmds = cellTex, rowname=NULL)
  @
  \\end{document}',
  file="tmp.Rnw" )
Sweave("tmp.Rnw")
library(utils)
texi2pdf("tmp.tex")