ecodist (version 1.01)

crosstab: Data formatting

Description

Converts field data of the form site, species, observation into a matrix.

Usage

crosstab(rowlab, collab, values, type = "sum")

Arguments

rowlab

row labels, e.g. site names.

collab

column labels, e.g. species names.

values

data values.

type

function to use to combine data, one of "sum" (default), "min", "max", "mean".

Value

• matrix with rowlab as row headings, collab as columns, and values as the data.

Details

Field data are often recorded as a separate row for each site-species combination. This function turns them into a matrix for further analysis based on unique row and column labels.

The three vectors should all be the same length (including duplicates).

Examples

# Make a random example
plotnames <- sort(rep(1:5, 3))
speciesnames <- rep(c("A", "B", "C"), 5)
freqdata <- runif(15)

data.m <- crosstab(plotnames, speciesnames, freqdata)