count combined occurrences of categories
On Jan 11, 2013, at 2:54 AM, Biau David wrote:
Dear all,
i would like to count the number of times where I have combined
occurrences of the categories of 2 variables.
For instance, in the dataframe below, i would like to know how many
times each author (au1, au2, au3 represent the first, second, third
author) is associated with each of the category of the variable
'nam'. The position of the author does not matter.
nam <- c('da', 'ya', 'da', 'da', 'fr', 'fr', 'fr', 'da', 'ya', 'fr')
au1 <- c('deb', 'art', 'deb', 'seb', 'deb', 'deb', 'mar', 'mar',
'joy', 'joy')
au2 <- c('art', 'deb', 'mar', 'deb', 'joy', 'mar', 'art', 'lio',
'nem', 'mar')
au3 <- c('mar', 'lio', 'joy', 'mar', 'art', 'lio', 'nem', 'art',
'deb', 'tat')
tutu <- data.frame(cbind(nam, au1, au2, au3))
You should first abandon the practice of using `cbind` inside
`data.frame`. Obscure errors will plague your R experience until you
do so.
Bas solution:
> tutus <- data.frame(nam=tutu$nam, au=with(tutu, c(au1,au2,au3)))
> tutab <- with(tutus, table(nam, au) )
> tutab
au
nam 1 2 3 4 5 6 7
da 2 3 1 2 4 0 0
fr 2 2 2 2 2 1 1
ya 1 2 1 1 0 1 0
David Winsemius, MD Alameda, CA, USA