[R] Row-wise recurive function call

[David Winsemius]

On Nov 9, 2010, at 3:28 AM, Santosh Srinivas wrote:

> Thanks this works. Only, I need to reference in the formula using  
> indexes.

Then you need to use the indices inside plaFn.

playFn<- function (x){
   result = ((x[1]+6*x[2])/(3*x[3])+20)*x[4]
   return(result)
   }

>
>
> -----Original Message-----
> From: Dimitris Rizopoulos [mailto:d.rizopoulos at erasmusmc.nl]
> Sent: 09 November 2010 13:22
> To: Santosh Srinivas
> Cc: r-help at r-project.org
> Subject: Re: [R] Row-wise recurive function call
>
> try this:
>
> apply(data.matrix(a), 1, playFn)
>
>
> I hope it helps.
>
> Best,
> Dimitris
>
>
> On 11/9/2010 8:32 AM, Santosh Srinivas wrote:
>> Dear Group,
>>
>> I have a following dataset:
>>> a
>>     A  B  C  D
>> 1  22  3 31 40
>> 2  26 31 36 32
>> 3   3  7 49 16
>> 4  24 40 27 26
>> 5  20 45 47  0
>> 6  34 43 11 18
>> 7  48 48 24  2
>> 8   3 16 39 48
>> 9  20 49  7 21
>> 10 17 36 47 10
>>
>>> dput(a)
>> structure(list(A = c(22L, 26L, 3L, 24L, 20L, 34L, 48L, 3L, 20L,
>> 17L), B = c(3L, 31L, 7L, 40L, 45L, 43L, 48L, 16L, 49L, 36L),
>>     C = c(31L, 36L, 49L, 27L, 47L, 11L, 24L, 39L, 7L, 47L), D =  
>> c(40L,
>>     32L, 16L, 26L, 0L, 18L, 2L, 48L, 21L, 10L)), .Names = c("A",
>> "B", "C", "D"), class = "data.frame", row.names = c(NA, -10L))
>>
>>
>> I have a function that works off EVERY individual ROW to throw a  
>> result.
>> Like
>>
>> playFn<- function (x){
>> + result = ((x$A+6*x$B)/(3*x$C)+20)*x$D
>> + return(result)
>> + }
>>
>>
>> I want to apply the function for every row .... can I use an "apply"
>> function ... tried but not been able to ...
>> e.g. print(rapply(a,playFn))
>>
>> Please advise.
>>
>> Thanks,
>> S
>>
>> ______________________________________________
>> 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.
>>
>
> -- 
> Dimitris Rizopoulos
> Assistant Professor
> Department of Biostatistics
> Erasmus University Medical Center
>
> Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
> Tel: +31/(0)10/7043478
> Fax: +31/(0)10/7043014
> Web: http://www.erasmusmc.nl/biostatistiek/
>
> ______________________________________________
> 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