I am trying to learn how to write R functions (really to program in R). I want
to write a function that will allow me to refer to the elements of a data frame
by column name, much as is done in lm. I can't seem to get the syntax correct.
I want the function to print the elements of data2[,"Mo6MONO"]
data2 <- data.frame(POSTHHMONO=c(1,2,3,4),Mo6MON=c(10,11,12,13))
data2
doit<- function(pre,post,data) {
element <- deparse(substitute(pre))
print(element)
frame <- deparse(substitute(data))
print(frame)
print(frame$element)
}
doit(Mo6MONO,POSTHHMONO,data2)
results of running function:
Browse[1]> doit(Mo6MONO,POSTHHMONO,data2)
[1] "Mo6MONO"
[1] "data2"
Error during wrapup: $ operator is invalid for atomic vectors
I have looked at lm, but don't understand the syntax, and have tried to run lm
so as to learn the syntax by just don't understand . . . .
HELP
Thanks
John
John David Sorkin M.D., Ph.D.
Professor of Medicine
Chief, Biostatistics and Informatics
University of Maryland School of Medicine Division of Gerontology and Geriatric
Medicine
Baltimore VA Medical Center
10 North Greene Street
GRECC (BT/18/GR)
Baltimore, MD 21201-1524
(Phone) 410-605-7119
(Fax) 410-605-7913 (Please call phone number above prior to faxing)
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