Phylogenetically Independent Orthonormal Contrasts
This function computes the orthonormal contrasts using the method described by Felsenstein (2008). Only a single trait can be analyzed; there can be several observations per species.
pic.ortho(x, phy, var.contrasts = FALSE, intra = FALSE)
x |
a numeric vector or a list of numeric vectors. |
phy |
an object of class |
var.contrasts |
logical, indicates whether the expected
variances of the contrasts should be returned (default to
|
intra |
logical, whether to return the intraspecific contrasts. |
The data x
can be in two forms: a vector if there is a single
observation for each species, or a list whose elements are vectors
containing the individual observations for each species. These vectors
may be of different lengths.
If x
has names, its values are matched to the tip labels of
phy
, otherwise its values are taken to be in the same order
than the tip labels of phy
.
either a vector of contrasts, or a two-column matrix with the
contrasts in the first column and their expected variances in the
second column (if var.contrasts = TRUE
). If the tree has node
labels, these are used as labels of the returned object.
If intra = TRUE
, the attribute "intra"
, a list of
vectors with the intraspecific contrasts or NULL
for the
species with a one observation, is attached to the returned object.
Emmanuel Paradis
Felsenstein, J. (2008) Comparative methods with sampling error and within-species variation: Contrasts revisited and revised. American Naturalist, 171, 713–725.
tr <- rcoal(30) ### a single observation per species: x <- rTraitCont(tr) pic.ortho(x, tr) pic.ortho(x, tr, TRUE) ### different number of observations per species: x <- lapply(sample(1:5, 30, TRUE), rnorm) pic.ortho(x, tr, intra = TRUE)
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