R help - Jun 2011 - Quick R syntax question

Hi --

I had a pretty quick R question since unfortunately I have not been able to
find an answer on Google.  It shouldn't take much more than a minute to
answer.

I'm trying to add up the major gleason grade and minor gleason grade for an
analysis of patients with prostate cancer.  One column has values under
"Major Gleason" and another column has values under "Minor
Gleason."  For
example,
Major Gleason     Minor Gleason
4                         3
5                         2
2                         4
3                         3

I want my output to be:
"4+3"
"5+2"
"2+4"
"3+3"

The quasi-pseudocode in Java is basically:

major = column$majorGleason
minor = column$minorGleason
for item in len(Major Gleason) {
  string s = major(item) "+" minor(item);
}
return s;

But trying the same idea in R:

string <- major "+" minor

gives me an error: "unexpected string constant in..."

I would greatly appreciate any help.

Thanks,

Ben

	[[alternative HTML version deleted]]

If we assume that your data are in a data frame (which doesn't allow
spaces in column names, hence the periods in the call below):
>df = data.frame(Major.Gleason = c(4,5,2,3), Minor.Gleason = c(3,2,4,3))
You can paste together the contents of the two columns with a plus
sign in between using the paste() function. The sep='' option at the
end of the function call specifies that no spaces should be included
between pasted items.
>output = paste(as.character(df [,'Major.Gleason']), '+',
as.character(df[ ,'Minor.Gleason']), sep='')
The new object 'output' is a character vector containing the 4 strings
you're after:
> print(output)
[1] "4+3" "5+2" "2+4" "3+3"


On Mon, Jun 20, 2011 at 11:31 AM, Ben Ganzfried <ben.ganzfried at
gmail.com> wrote:
>
> Hi --
>
> I had a pretty quick R question since unfortunately I have not been able to
> find an answer on Google. ?It shouldn't take much more than a minute to
> answer.
>
> I'm trying to add up the major gleason grade and minor gleason grade
for an
> analysis of patients with prostate cancer. ?One column has values under
> "Major Gleason" and another column has values under "Minor
Gleason." ?For
> example,
> Major Gleason ? ? Minor Gleason
> 4 ? ? ? ? ? ? ? ? ? ? ? ? 3
> 5 ? ? ? ? ? ? ? ? ? ? ? ? 2
> 2 ? ? ? ? ? ? ? ? ? ? ? ? 4
> 3 ? ? ? ? ? ? ? ? ? ? ? ? 3
>
> I want my output to be:
> "4+3"
> "5+2"
> "2+4"
> "3+3"
>
> The quasi-pseudocode in Java is basically:
>
> major = column$majorGleason
> minor = column$minorGleason
> for item in len(Major Gleason) {
> ?string s = major(item) "+" minor(item);
> }
> return s;
>
> But trying the same idea in R:
>
> string <- major "+" minor
>
> gives me an error: "unexpected string constant in..."
>
> I would greatly appreciate any help.
>
> Thanks,
>
> Ben
>
> ? ? ? ?[[alternative HTML version deleted]]
>
> ______________________________________________
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> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.


--
___________________________
Luke Miller
Postdoctoral Researcher
Marine Science Center
Northeastern University
Nahant, MA
(781) 581-7370 x318