It's probably easiest to think of this as a compound map (doctor -> dept
code -> factor -> character -> integer -> dept code -> dept name as
character) and to treat the code as such: if you already have R objects with
the codes in them, it shouldn't be hard to do the transformation.

Consider the following toy set up

Docs = factor(c("Greg Jones","Bob Smith","Al Franklin","Christian
Christianson"))
DocDepts = factor(c("9999","5555","9999","1111"))
Doctors = data.frame(Docs, DocDepts)

Depts = factor(1:9 * 1111)
DeptNames =
factor(c("Heart","Kidney","Feet","Teeth","Brain","Digestive","Diagnostic","Surgery","Anesthesia"))
DeptCodes = data.frame(Depts,DeptNames)
# Everything in our data frames is now some sort of factor so we can't match
things up in the "normal" ways

# Now, you have to do some unpleasantly long but pretty straightforward code
to convert the factors in a way that makes the match properly:

Doctors$numbers <- as.numeric(as.character(Doctors[,2])) ## Will extract the
"9999" as a real 9999, rather than the internal factor code
DeptCodes$values <- as.numeric(as.character(DeptCodes[,1]))

match(Doctors$numbers, DeptCodes$values) ## Will map the department numbers
onto the correct rows of the DeptCodes df

# Now we get the correct names using those row numbers
DeptAssignments = as.character(DeptCodes[match(Doctors$numbers,
DeptCodes$values),2])

# Combine with doctor names to finish
NamesandTitles = cbind(as.character(Doctors[,1]),DeptAssignments)

It's not the most elegant way of doing it, but hopefully it gives some
insight into how to work with factors. If you can send a little more
information about how your data is currently stored we can optimize this
into something easily repeatable but without specifics, I have to work in
generalities.

Hope this helps,

Michael Weylandt

On Thu, Sep 8, 2011 at 6:36 PM, Totally Inept <kramer877@gmail.com> wrote:

> First of all, let me apologize, as this is probably an absurdly basic
> question. I did search before asking, but perhaps my ineptitude didn't
> allow
> me to apply what I read to what I'm doing. Totally new to R, and haven't
> done any code in any language in a long time.
>
> Basically I've got categories. They're department codes for doctors (say,
> 9999 for radiology or 5555 for endocrinology), which of course means that
> there are a good number of them, i.e. it's not practical for me to write
> them all out as I usually see in examples of categorical variables
> (factors).
>
> And then I've got a list of doctors that I'm actually interested in. I have
> the department codes associated with each, but I need to map the department
> name to the doctor name. So I might have Greg Jones, Bob Smith, Tom Wilson,
> etc... to go with 1234, 9999, 2222, etc.
>
> I need to turn Greg Jones, Bob Smith, ... and 1234, 9999, ... into Greg
> Jones, Bob Smith, ... Cardiology, Radiology, ....
>
> Obviously I could just search and replace within the csv files but I need
> something durable that I can run things through repeatedly.
>
> Anyhow, thanks to anyone willing to humor me with an answer.
>
> --
> View this message in context:
> http://r.789695.n4.nabble.com/Factors-I-think-tp3800413p3800413.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

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