[R] trouble calculating rates--sometimes the denominator is missing

[Christopher W. Ryan]

One more bit:  I got as far as this, thinking it might help:

Using a data file that I know has all the necessary denominators, I 
created a dataframe of school names (as factor) and TotalStudentsEnrolled.

  data.frame(data$School[!duplicated(data$School)], 
data$TotalStudentsEnrolled[!duplicated(data$School)])

1    BENJAMIN FRANKLIN ES            465
2    CALVIN COOLIDGE SCHL            379
3    EAST MS                         590
4    HORACE MANN SCHL                374
5    MAC ARTHUR SCHL                 481
6    THEO ROOSEVELT SCHL             377
[truncated]

I thought I might be able to "look up" the necessary value for each 
school from this dataframe. But I can't get my head around using indices 
to do it.

Thanks again.

--Chris

-- 
Christopher W. Ryan, MD
SUNY Upstate Medical University Clinical Campus at Binghamton
425 Robinson Street, Binghamton, NY  13904
cryanatbinghamtondotedu

"If you want to build a ship, don't drum up the men to gather wood, 
divide the work and give orders. Instead, teach them to yearn for the 
vast and endless sea."  [Antoine de St. Exupery]