[R] Recoding categorical variables

[Murray Jorgensen]

Thanks John! Deepayan Sarkar also suggested this. I don't really expect 
to see any better solution.  Murray

John Fox wrote:
> Dear Murray,
> 
> How about as.numeric(factor(y)) ?
> 
> I hope this helps,
>  John
> 
> --------------------------------
> John Fox
> Department of Sociology
> McMaster University
> Hamilton, Ontario
> Canada L8S 4M4
> 905-525-9140x23604
> http://socserv.mcmaster.ca/jfox 
> -------------------------------- 
> 
>> -----Original Message-----
>> From: r-help-bounces at stat.math.ethz.ch 
>> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Murray 
>> Jorgensen
>> Sent: Wednesday, October 25, 2006 7:13 PM
>> To: r-help at stat.math.ethz.ch
>> Subject: [R] Recoding categorical variables
>>
>> I want to recode an integer-valued variable y so that its 
>> values become 1:length(y). I can do this using a loop but 
>> maybe someone can suggest code without a loop. My code is this:
>>
>> y <- round(20*runif(25))
>> table(y)
>> suy <- sort(unique(y))
>> m <- length(suy)
>> z <- y + max(suy)
>> for(i in 1:m) z[y==suy[i]] <- i
>> rbind(y,z)
>>
>> (the recoded y is stored in z)
>>
>> Murray Jorgensen
>> -- 
>> Dr Murray Jorgensen      http://www.stats.waikato.ac.nz/Staff/maj.html
>> Department of Statistics, University of Waikato, Hamilton, New Zealand
>> Email: maj at waikato.ac.nz                                Fax 7 838 4155
>> Phone  +64 7 838 4773 wk    Home +64 7 825 0441    Mobile 021 1395 862
>>
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>> and provide commented, minimal, self-contained, reproducible code.
> 

-- 
Dr Murray Jorgensen      http://www.stats.waikato.ac.nz/Staff/maj.html
Department of Statistics, University of Waikato, Hamilton, New Zealand
Email: maj at waikato.ac.nz                                Fax 7 838 4155
Phone  +64 7 838 4773 wk    Home +64 7 825 0441    Mobile 021 1395 862