Cperiodogram {adespatial}R Documentation

Contingency periodogram

Description

Function to compute a contingency periodogram for a univariate series of qualitative data

Usage

Cperiodogram(x, T1 = 2, T2 = NULL, nperm = NULL, alpha = 0.05, graph = TRUE)

Arguments

x

a qualitative variable (factor)

T1

first period included in the calculations (default: T1 = 2)

T2

last period included in the calculations (default: T2 = n/2)

nperm

Number of permutations for the chi-square test. For chi-square tests using the chi- square distribution, use the default nperm=NULL

alpha

significance level for computation of the confidence limits

graph

a logical indicating if a graph is requested, by default TRUE.

Details

The contingency periodogram of Legendre et al. (1981) identifies periodic components in qualitative data vectors. The vector may contain classes of a qualitative variable or the classes obtained by hierarchical clustering or partitioning of a multivariate data table. The method is also described in Legendre & Legendre (2012). The optional graph produced by the function shows the following information:

Value

A table with the statistics for the selected periods:

Confidence interval limits:

Author(s)

Pierre Legendre pierre.legendre@umontreal.ca

References

Legendre, L., M. Fr├ęchette & P. Legendre. 1981. The contingency periodogram: a method of identifying rhythms in series on nonmetric ecological data. Journal of Ecology 69: 965-979.

Legendre, P. and Legendre, L. 2012. Numerical Ecology. 3rd English ed. Elsevier, Amsterdam

Examples

# Data from the numerical example of Subsection 12.4.2 of Legendre and Legendre (2012).
test.vec <- c(1,1,2,3,3,2,1,2,3,2,1,1,2,3,3,1)
# Periodogram with tests using the chi-square distribution
res <- Cperiodogram(test.vec)
# Periodogram with permutation tests
res <- Cperiodogram(test.vec, nperm=2000, graph=FALSE)


[Package adespatial version 0.3-14 Index]