[R] multiple values in one column

[John D. Muccigrosso]

On Apr 6, 2012, at 9:09 AM, John D. Muccigrosso wrote:

> I have some data files in which some fields have multiple values. For example
> 
> first  last   sex   major
> John   Smith  M     ANTH
> Jane   Doe    F     HIST,BIOL
> 
> What's the best R-like way to handle these data (Jane's major in my example), so that I can do things like summarize the other fields by them (e.g., sex by major)?
> 
> Right now I'm processing the files (in excel since they're spreadsheets) by duplicating lines with two values in the major field, eliminating one value per row. I suspect there's a nifty R way to do this.


I've gotten a few responses, for which I'm grateful, but either I don't quite see how they answer my question, or I didn't phrase my question well, both of which are equally possible. :-)

So, given the data as above, let's call it "students", I have no problem turning it into:

first  last   sex   major
John   Smith  M     ANTH
Jane   Doe    F     HIST
Jane   Doe    F     BIOL

What I then do with this is things like 

table(students$sex, students$major)

So, three steps:

1. Get data with multiple values per field.
2. Turn it into a data frame with only one value per field (by duplicating lines).
3. Do things like table().

I'd like to be able to skip #2.

Thanks.

John Muccigrosso