Randomizes a binary matrix speciesData by reshuffling all
elements. Columns are equiprobable, and rows are proportional to row sums.
Makes a call to the vector_sample function.
Returns a binary presence-absence matrix with the same
dimensions and fill as the input matrix.
Details
This algorithm assumes that sites are equiprobable, but that
differences in frequency of occurrence among species are proportional to
observed species richness (=colsums).
References
Gotelli, N.J. 2000. Null model analysis of species co-occurrence
patterns. Ecology 81: 2606-2621.