[R] Quick R syntax question

[David Winsemius]

On Jun 20, 2011, at 11:47 AM, Luke Miller wrote:

> 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='')

I do not think the as.character is needed. Coercion to character is  
implicit in the use of paste(). And  the sep argument could be "+".

output = paste(df [,'Major.Gleason'],  df[ ,'Minor.Gleason'], sep='+')

-- 
David.

>
> 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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>> 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.
>
>
>
> --
> ___________________________
> Luke Miller
> Postdoctoral Researcher
> Marine Science Center
> Northeastern University
> Nahant, MA
> (781) 581-7370 x318
>
> ______________________________________________
> R-help at 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.

David Winsemius, MD
West Hartford, CT