[R] easier way to print heatmap on multiple pages?

[Jake Michaelson]

Hi All,

I've worked on some code to take a heatmap with 1000 row entries, and 
split this up into 20 pages, each with 50 rows from the original 
heatmap.  I want to preserve the row order such that all 20 pages, if 
put together, would comprise the original heatmap.

Here's what I've done:

##make the initial heatmap, with all 1000 rows and write it to an 
object 'heatAll'
heatAll = heatmap.2(combined.int.top, col = cm.colors(256), trace = 
"none")


  pdf(file="~/Desktop/Alfalfa-Ladak-StemV3.pdf", width=8, height=12, 
pointsize=4)
for(i in 1:20){
   selected = heatAll$rowInd[((i-1)*50):((i-1)*50+50)] ##get original 
row order in groups of 50

   heatmap.2(combined.int.top[selected,], Rowv = FALSE, ##prevent row 
re-ordering
   Colv=heatAll$colInd,
   col=cm.colors(256),
   trace="none", margins = c(9,8),
   main=paste("page", i, sep=" "))

  }
  dev.off()

I can't think of why this wouldn't work, but for some reason things are 
completely out of order.  For example, the first page of the PDF shows 
many genes found at the bottom of the original heatmap, but in a 
different order.  Strange.

So, have I made this insanely complicated?  Is there an easier, better 
way to print a large heatmap on multiple pages?

Thanks in advance for any help.

--Jake