[R] Count of unique factors within another factor

[jim holtman]

You can also use the sqldf package:

> x
   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
> require(sqldf)
> sqldf('select unit, count(distinct species) as count from x group by unit')
  unit count
1  123     3
2  345     4
>


On Sun, Jun 13, 2010 at 12:07 PM, Birdnerd <haaszoology at gmail.com> 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--
>
> --
> View this message in context: http://r.789695.n4.nabble.com/Count-of-unique-factors-within-another-factor-tp2253545p2253545.html
> Sent from the R help mailing list archive at Nabble.com.
>
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>



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

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