Re: [R] Count of unique factors within another factor

From: Erik Iverson <eriki_at_ccbr.umn.edu>
Date: Sun, 13 Jun 2010 13:08:57 -0500

I think ?tapply will help here. But *please* read the posting guide and provide minimal, reproducible examples!

Birdnerd wrote:
> I have a data frame with two factors (sampling 'unit', 'species'). I want to
> calculate the number of unique 'species' per 'unit.' I can calculate the
> number of unique values for each variable separately, but can't get a count
> for each ‘unit’.
>

>> data=read.csv("C:/Desktop/sr_sort_practice.csv")
>> attach(data)

>
>> data[1:10,]

> unit species
> 1 123 ACMA
> 2 123 LIDE
> 3 123 LIDE
> 4 123 SESE
> 5 123 SESE
> 6 123 SESE
> 7 345 HEAR
> 8 345 LOHI
> 9 345 QUAG
> 10 345 TODI…..
>
>> sr.unique<- lapply (data, unique)

> $unit
> [1] 123 345 216
> $species
> [1] ACMA LIDE SESE HEAR LOHI QUAG TODI UMCA ARSP LIDE
>
>> sapply (sr.unique,length)

> unit species
> 3 10
>
> Then, I get stuck here because this unique species count is not given for
> each ‘unit’.
> What I'd like to get is:
>
> unit species
> 123 3
> 345 4
> 216 --
>
> Thanks--
>

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. Received on Sun 13 Jun 2010 - 18:11:01 GMT

Archive maintained by Robert King, hosted by the discipline of statistics at the University of Newcastle, Australia.
Archive generated by hypermail 2.2.0, at Mon 14 Jun 2010 - 16:50:30 GMT.

Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-help. Please read the posting guide before posting to the list.

list of date sections of archive