Remove NAs from Barplot

Dear List:

I'm creating a series of barplots using Sweave that must assume a 
standard format. This is student achievement data and the x-axis must 
include all grades 3 to 8. In some cases, the data for a grade (or 
more than one grade) are missing in the vector math.bar, but are never

missing for the vector apmxpmeet. The following sample code 
illustrates the issue.

Using the code below to create the plot works fine. However, the 
following command is designed to place the data onto the plot:

text(math.barplot, graph.max+5, format(tot), xpd = TRUE, col = 
c("blue",
"orange") )

This does work, but, it also places 'NA's on the plot. Is there a way 
to place the data onto the plot such that the numbers appear, but for 
the NAs not to appear?  I've searched through ?text but was not able 
to find a solution.

math.bar <- c(NA,NA,NA,NA,55,48)
apmxpmeet <- c(47, 50, 49, 50, 49, 46)

par(ps=10)
math.bar <- rbind(math.bar, apmxpmeet) math.barplot <- 
barplot(math.bar, beside=T, col=c('blue','orange'), names=c('Grade \n 
3','Grade \n 4','Grade \n 5','Grade \n 6','Grade \n 7','Grade \n 8'), 
ylim=c(0,120), ylab="Percentage", xlab="Grade Level") tot <- 
round(math.bar,digits=0) graph.max <- max(math.bar, apmxpmeet, 
na.rm=T) text(math.barplot, graph.max+5, format(tot), xpd = TRUE, col 
= c("blue",
"orange") )
tmp$sch_nameS05 <- as.character(tmp$sch_nameS05) 
legend(2,120,legend=(c(tmp$sch_nameS05, "Average")),
fill=c("blue","orange"))

Thanks,
Harold

format(tot)

tot

tmp$sch_nameS05 <- as.character(tmp$sch_nameS05)