[R] Count factor if

[mathijsdevaan]

Thanks! That solved the problem.


Dimitris Rizopoulos-4 wrote:
> 
> try this:
> 
> x <- factor(c('a','a','a','a','a','b','b','b','c','d','d','d'))
> y <- c(1,3,6,8,8,3,4,7,5,6,7,10)
> X <- data.frame(x, y)
> 
> cbind(X, z = ave(X$y, X$x,
>      FUN = function (x) match(x, unique(x)) - 1))
> 
> 
> I hope it helps.
> 
> Best,
> Dimitris
> 
> 
> On 2/17/2011 11:15 AM, mathijsdevaan wrote:
>>
>>> Here is a method that works despite generating a warning:
>>> cbind(X, z = ave(X$y, X$x, FUN = seq) - 1)
>>>
>>> David Winsemius, MD
>>> West Hartford, CT
>>
>> I was happy a bit too early. There's still an error:
>>
>> x<-as.factor(c('a','a','a','a','a','b','b','b','c','d','d','d'))
>> y<-c(1,3,6,8,8,3,4,7,5,6,7,10)
>> X<-data.frame(x,y)
>> X
>>     x  y
>> 1  a  1
>> 2  a  3
>> 3  a  6
>> 4  a  8
>> 5  a  8
>> 6  b  3
>> 7  b  4
>> 8  b  7
>> 9  c  5
>> 10 d  6
>> 11 d  7
>> 12 d 10
>>
>> cbind(X, z = ave(X$y, X$x, FUN = seq) - 1)
>>
>>     x  y z
>> 1  a  1 0
>> 2  a  3 1
>> 3  a  6 2
>> 4  a  8 3
>> 5  a  8 4
>> 6  b  3 0
>> 7  b  4 1
>> 8  b  7 2
>> 9  c  5 0
>> 10 d  6 0
>> 11 d  7 1
>> 12 d 10 2
>>
>> Using this function provides a value of 4 in row 5, column c, while it
>> should be 3. Is there another way I can solve my problem? Thanks!
>>
>> M
> 
> -- 
> 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/
> 
> ______________________________________________
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> 
> 

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