Description Usage Arguments Value Author(s) References See Also Examples
Given a matrix M and a beta diversity measure f, the function calculates the p-values of f based on the permutation null model.
1 | permutation.pvalues.b(matrix, f, args, observed.vals, reps=1000)
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matrix |
A matrix with integer values. The matrix should not contain any NA values. |
f |
A beta diversity function f. The interface of f should be such that f(matrix,args) returns a matrix V where the entry stored at the i-th row and j-th column of V is equal to the value of f when applied at the i-th and j-th row of the input matrix. To fit this interface, the user might have to develop f as a wrapper around an existing R function (see Examples). |
args |
A list with extra arguments needed by f. |
observed.vals |
A set of pre-calculated values for which we want to compute their p-values. |
reps |
The number of randomizations. This argument is optional and its default value is set to one thousand. |
A numeric vector that stores the p-values of f, calculated based on the permutation null model. The i-th element of the vector stores the p-value for the i-th element in vector observed.vals.
Constantinos Tsirogiannis (tsirogiannis.c@gmail.com)
Gotelli, N. J., 2000. Null Model Analysis of Species Co-Occurrence Patterns. Ecology, 81(9), pp.2606-2621.
Tsirogiannis, C., A. Kalvisa, B. Sandel and T. Conradi. Column-Shuffling Null Models Are Simpler Than You Thought. To appear.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 | #In the next example null-model calculations are
#performed using a function of phylogenetic diversity.
#Hence, we first load the required packages.
require(CNull)
require(ape)
require(PhyloMeasures)
#Load phylogenetic tree of bird families from package "ape"
data(bird.families, package = "ape")
#Create 100 random communities with 50 families each
comm = matrix(0,nrow = 100,ncol = length(bird.families$tip.label))
for(i in 1:nrow(comm)) {comm[i,sample(1:ncol(comm),50)] = 1}
colnames(comm) = bird.families$tip.label
#Set function f to be the Common Branch Length measure (CBL)
#as defined in the R package PhyloMeasures.
my.f = function(mt,args){ return (cbl.query(args[[1]],mt))}
# This function takes one extra argument, which is a phylogenetic tree.
# Hence, create a list whose only element is the desired tree.
arguments = list()
arguments[[1]] = bird.families
#Compute the values of f for all pairs of observed communities in M.
#Turn the resulting matrix with the observed diversity values into a vector
obs.v=my.f(comm,arguments)
vals = as.vector(t(obs.v))
# Calculate the p-values of f for the communities in comm
# based on the permutation model, using 2000 Monte Carlo randomizations.
permutation.pvalues.b(comm,f=my.f,args=arguments,observed.vals=vals,reps=2000)
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