simba (version 0.3-4)

bb2num: Transform Braun-Blanquet scale data to percentage cover values and vice versa

Description

The function allows for an easy transformation of Braun-Blanquet (or any other phytosciological scale) data to numeric values for numerical analysis or vice versa. Be aware that this transformation is not losless regarding the information content.

Usage

bb2num(dat, from = c("r", "+", "1", "2", "3", "4", "5"), 
to = c(0.1, 1, 5, 15, 37.5, 62.5, 87.5))

Arguments

dat

A species matrix.

from

Definition of the imput scale. Per default the transformation is done from the classic Braun-Blanquet scale to cover percentages. For transformation from numerical values to a phytosociological scale see details and example.

to

Definition of the output scale. The default are the recommended class centers when transforming BB to percentage cover values. Can be changed according to your needs. See details.

Value

• Returns a species matrix in the specified format.

encoding

UTF-8

Details

When transforming from a phytosociological scale to Braun-Blanquetfrom and to have to be the same length. In case of transformation from numerical cover values to a phytosociological scale the function expects a numerical vector in from that, for each class, gives the lower and upper limit. Thus, length(from) == 2*length(to) in this case.

Examples

## Create a species that occurs on 7 plots
## with all the different possibilities of
## the BB scale
spec <- c("r", "+", "0", "1", "2", "3", "4", "5")

## Create a highly artificial species matrix.
## All species are the same for simplicity 
dat.bb <- data.frame(spec, spec, spec, spec, spec, spec)

## Transform from BB scale to percentage values
dat.proc <- bb2num(dat.bb)

## When transforming back the class definitions are a little
## more complicated. Just give the lower and upper limits for
## each class in the from vector class for class.
from <- c(0, 0.1, 0.1, 2, 2, 5, 5, 25, 25, 50, 50, 75, 75, 100)
to <- c("r", "+", "1", "2", "3", "4", "5")
bb2num(dat.proc, from=from, to=to)