# S4 method for matrix
# S4 method for data.frame
A \(m \times p\)
data.frame of count data (absolute frequencies giving the number of
individuals for each category, i.e. a contingency table). A
will be coerced to a
Currently not used.
A co-occurrence matrix is a symmetric matrix with zeros on its main
diagonal, which works out how many times each pairs of taxa/types occur
together in at least one sample.
## Data from Conkey 1980, Kintigh 1989
## Plot spot diagram of a co-occurrence matrix
occ <- occurrence(cantabria)