[R] Using 'field names' of a data.frame in a function

Polwart Calum (County Durham and Darlington NHS Foundation Trust) calum.polwart at nhs.net
Thu Aug 6 21:50:27 CEST 2009

I may be doing this wrong!  but I have a function which I have simplified a lot below.  I want to pass some 'field names' of a data-frame to the function for it to then do some manipulation of.

Here's my code:
#build a simple dataset
 mydataset = data.frame ( ages=c('40-49','40-49','40-49','30-39','50-59','50-59','60-69','50-59'),  sex = c("M","F","F","M","F","F","M","M"))

#build a simple function
 myfunc <- function (categories) {
   table (categories)

#call the function
myfunc (c(mydataset$ages, mydataset$sex))


My output I am getting is:
1 2 3 4
5 7 3 1

But what I'm expecting is:
table (mydataset$ages, mydataset$sex)

        F M
  30-39 0 1
  40-49 2 1
  50-59 2 1
  60-69 0 1

Calling the function as:  myfunc ("mydataset$ages, mydataset$sex") doesn't work either and nor does myfunc (c("mydataset$ages", "mydataset$sex"))

Now in the simple version above I could make the function (category1, category2) and then call table (category1, category2) - but what if I might have a category 3, category 4 etc... How can I pass the dataset name to the function without it trying to actually pass the data to the function?  I've also tried paste - but perhaps I'm mis-using it?

Many thanks for help in advance


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