[R] How to apply table() on subdata and stack outputs

jim holtman jholtman at gmail.com
Wed Feb 11 20:07:27 CET 2009


This may be what you want:

> table(input.df$id, input.df$var_interest)

         happy soso unhappy
  jack 0     2    1       1
  tom  1     1    0       1


On Wed, Feb 11, 2009 at 1:34 PM, Sean Zhang <seanecon at gmail.com> wrote:
> Dear R helpers:
>
> I am a R novice and have a question about using table() to extract
> frequences over many sub-datasets.
> A small example input dataframe and wanted output dataframe are provided
> below. The real data is very large so a for loop is what I try to avoid.
>
> Can someone englithen me how to use sapply or the like to achieve it?
>
> Many thanks in advance!
>
> -Sean
>
> #example input dataframe
> id <- c('tom', 'tom', 'tom', 'jack', 'jack', 'jack', 'jack')
> var_interest <- c("happy","unhappy", "", "happy", "unhappy", 'soso','happy')
> input.df <- data.frame(id=id, var_interest=var_interest)
> input.df
> wanted.df <-
>
> #output dataframe I want
> id_unique <- c('tom','jack')
> happy_freq<-c(1,2)
> unhappy_freq<-c(1,1)
> soso_freq<-c(0,1)
> miss_freq<-c(1,0)
> output.df <-data.frame(id_unique=id_unique, happy_freq=happy_freq,
> unhappy_freq=unhappy_freq, soso_freq=soso_freq, miss_freq=miss_freq)
> output.df
>
>        [[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.
>



-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?



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