title: Using the R forestplot package, is there a way to assign variable colors to boxes?
body: <p>As an example, I will use the code from the R forestplot vignette (<a href="https://cran.r-project.org/web/packages/forestplot/vignettes/forestplot.html" rel="nofollow">https://cran.r-project.org/web/packages/forestplot/vignettes/forestplot.html</a>):</p>
  
  <pre><code>library(forestplot)
  # Cochrane data from the 'rmeta'-package
  cochrane_from_rmeta &lt;- 
    structure(list(
      mean  = c(NA, NA, 0.578, 0.165, 0.246, 0.700, 0.348, 0.139, 1.017, NA, 0.531), 
      lower = c(NA, NA, 0.372, 0.018, 0.072, 0.333, 0.083, 0.016, 0.365, NA, 0.386),
      upper = c(NA, NA, 0.898, 1.517, 0.833, 1.474, 1.455, 1.209, 2.831, NA, 0.731)),
      .Names = c("mean", "lower", "upper"), 
      row.names = c(NA, -11L), 
      class = "data.frame")
  
  tabletext&lt;-cbind(
    c("", "Study", "Auckland", "Block", 
      "Doran", "Gamsu", "Morrison", "Papageorgiou", 
      "Tauesch", NA, "Summary"),
    c("Deaths", "(steroid)", "36", "1", 
      "4", "14", "3", "1", 
      "8", NA, NA),
    c("Deaths", "(placebo)", "60", "5", 
      "11", "20", "7", "7", 
      "10", NA, NA),
    c("", "OR", "0.58", "0.16", 
      "0.25", "0.70", "0.35", "0.14", 
      "1.02", NA, "0.53"))
  
  forestplot(tabletext, 
         cochrane_from_rmeta,new_page = TRUE,
         is.summary=c(TRUE,TRUE,rep(FALSE,8),TRUE),
         clip=c(0.1,2.5), 
         xlog=TRUE, 
         col=fpColors(box="royalblue",line="darkblue", summary="royalblue"))
  </code></pre>
  
  <p>Rather than having all the boxes be the same color, I would like to color the boxes based on the value of another variable.  I modified the example code, adding another column ("test") to cochrane_from_rmeta and would like to color the boxes based on the value of "test".  I would imagine the code should look like this:</p>
  
  <pre><code>library(forestplot)
  # Cochrane data from the 'rmeta'-package
  cochrane_from_rmeta &lt;- 
    structure(list(
      mean  = c(NA, NA, 0.578, 0.165, 0.246, 0.700, 0.348, 0.139, 1.017, NA, 0.531), 
      lower = c(NA, NA, 0.372, 0.018, 0.072, 0.333, 0.083, 0.016, 0.365, NA, 0.386),
      upper = c(NA, NA, 0.898, 1.517, 0.833, 1.474, 1.455, 1.209, 2.831, NA, 0.731)),
      test = c(NA,NA,1,3,1,7,4,9,6,NA,2)),
      .Names = c("mean", "lower", "upper", "test"), 
      row.names = c(NA, -11L), 
      class = "data.frame")
  
  tabletext&lt;-cbind(
    c("", "Study", "Auckland", "Block", 
      "Doran", "Gamsu", "Morrison", "Papageorgiou", 
      "Tauesch", NA, "Summary"),
    c("Deaths", "(steroid)", "36", "1", 
      "4", "14", "3", "1", 
      "8", NA, NA),
    c("Deaths", "(placebo)", "60", "5", 
      "11", "20", "7", "7", 
      "10", NA, NA),
    c("", "OR", "0.58", "0.16", 
      "0.25", "0.70", "0.35", "0.14", 
      "1.02", NA, "0.53"))
  
  forestplot(tabletext, 
         cochrane_from_rmeta,new_page = TRUE,
         is.summary=c(TRUE,TRUE,rep(FALSE,8),TRUE),
         clip=c(0.1,2.5), 
         xlog=TRUE, 
         col=fpColors(box=cochrane_from_rmeta$test,line="darkblue", summary="royalblue"))
  </code></pre>
  
  <p>However, doing this makes the boxes disappear.  Is there a way to color the boxes based on the value of "test", or is forestplot unable to handle a vector of colors?</p>