R, knitr, xtable, alternating row colors

Question

I'm trying to produce a table with xtable in R using knitr with alternating row colors. I can print a table in the PDF output but can't quite figure out the add.to.row command in the xtable manual along with the colortbl package.

Answer 1

This figure was produced using the code at the bottom. I hope you don't break your eyes detecting the light grey color (I almost have, on one of my screens).

library(xtable) mydf <- data.frame(id = 1:10, var1 = rnorm(10), var2 = runif(10)) rws <- seq(1, (nrow(mydf)-1), by = 2) col <- rep("\\rowcolor[gray]{0.95}", length(rws)) print(xtable(mydf), booktabs = TRUE,       add.to.row = list(pos = as.list(rws), command = col)) 

The key is to define row indices (rws) and their respective colors (col). If you want colors to differ between rows, you'll need to play around with paste.

\documentclass[a4paper]{article} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage[english]{babel} \usepackage{booktabs} \usepackage{colortbl, xcolor}  \begin{document}  <<do_table, results = "asis">>= library(xtable) mydf <- data.frame(id = 1:10, var1 = rnorm(10), var2 = runif(10)) rws <- seq(1, (nrow(mydf)), by = 2) col <- rep("\\rowcolor[gray]{0.95}", length(rws)) print(xtable(mydf), booktabs = TRUE,     add.to.row = list(pos = as.list(rws), command = col)) @  \end{document}