mem: Function to compute Moran's Eigenvector Maps (MEM) of a listw...

In adespatial: Multivariate Multiscale Spatial Analysis

Description

These functions compute MEM (i.e., eigenvectors of a doubly centered spatial weighting matrix). Corresponding eigenvalues are linearly related to Moran's index of spatial autocorrelation.

Usage

scores.listw(listw, wt = rep(1, length(listw$neighbours)),
  MEM.autocor = c("non-null", "all", "positive", "negative"))

mem(listw, wt = rep(1, length(listw$neighbours)),
  MEM.autocor = c("non-null", "all", "positive", "negative"))

orthobasis.listw(listw, wt = rep(1, length(listw$neighbours)),
  MEM.autocor = c("non-null", "all", "positive", "negative"))

Arguments

listw	An object of the class listw created by functions of the spdep package
wt	A vector of weights. It is used to orthogonalize the eigenvectors. It could be useful if MEM are used in weighted regression or canonical correspondence analysis
MEM.autocor	A string indicating if all MEMs must be returned or only those corresponding to non-null, positive or negative autocorrelation

Details

Testing the nullity of eigenvalues is based on E(i)/E(1) where E(i) is i-th eigenvalue and E(1) is the maximum absolute value of eigenvalues

Value

An object of class orthobasisSp , subclass orthobasis

Author(s)

St<c3><a9>phane Dray [e-mail]

References

Dray, S., Legendre, P., and Peres-Neto, P. R. (2006). Spatial modeling: a comprehensive framework for principal coordinate analysis of neighbor matrices (PCNM).Ecological Modelling 196, 483–493.

Griffith D. A. (1996) Spatial autocorrelation and eigenfunctions of the geographic weights matrix accompanying geo-referenced data. Canadian Geographer 40, 351–367.

See Also

nb2listw orthobasis

Examples

if(require("ade4", quietly = TRUE) & require("spdep", quietly = TRUE)){
data(oribatid)
nbtri <- tri2nb(as.matrix(oribatid$xy))
sc.tri <- scores.listw(nb2listw(nbtri, style = "B"))
summary(sc.tri)
}
if(require("adegraphics", quietly = TRUE)){
s.value(oribatid$xy,sc.tri[,1:9])
plot(sc.tri[,1:6], oribatid$xy, pSp.cex = 3)
}

Example output

Attaching package: 'ade4'

The following object is masked from 'package:adespatial':

    multispati


Attaching package: 'spdep'

The following object is masked from 'package:ade4':

    mstree


     PLEASE NOTE:  The components "delsgs" and "summary" of the
 object returned by deldir() are now DATA FRAMES rather than
 matrices (as they were prior to release 0.0-18).
 See help("deldir").
 
     PLEASE NOTE: The process that deldir() uses for determining
 duplicated points has changed from that used in version
 0.0-9 of this package (and previously). See help("deldir").


Orthonormal basis: data.frame with 70 rows and 69 columns
----------------------------------------------------------------
Columns form a centred orthonormal basis (i.e. 1n-orthogonal)
for the inner product defined by the 'weights' attribute
----------------------------------------------------------------

Attributes:
- names: MEM1 ... MEM69 
- row.names: 1 ... 70 
- weights: 0.01428571 ... 0.01428571 
- values: 0.07805391 ... -0.04134591 
- class: orthobasisSp orthobasis data.frame 
- call: scores.listw(listw = nb2listw(nbtri, style = "B")) 


Attaching package: 'adegraphics'

The following objects are masked from 'package:ade4':

    kplotsepan.coa, s.arrow, s.class, s.corcircle, s.distri, s.image,
    s.label, s.logo, s.match, s.traject, s.value, table.value,
    triangle.class

adespatial documentation built on May 2, 2019, 4:43 p.m.