On Sun, 13 Jun 2010, 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’.
If I understand you
colSums( xtabs( ~ specie + unit , data ) !=0 )
HTH,
Chuck
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--
--
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Charles C. Berry (858) 534-2098
Dept of Family/Preventive Medicine
E mailto:cbe...@tajo.ucsd.edu UC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/ La Jolla, San Diego 92093-0901
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