sp.correlogram {spdep} | R Documentation |
Spatial correlograms for Moran's I and the autocorrelation coefficient, with print and plot helper functions.
sp.correlogram(neighbours, var, order = 1, method = "corr", style = "W", randomisation = TRUE, zero.policy = NULL, spChk=NULL) ## S3 method for class 'spcor' plot(x, main, ylab, ylim, ...) ## S3 method for class 'spcor' print(x, p.adj.method="none", ...)
neighbours |
an object of class |
var |
a numeric vector |
order |
maximum lag order |
method |
"corr" for correlation, "I" for Moran's I, "C" for Geary's C |
style |
|
randomisation |
variance of I or C calculated under the assumption of randomisation, if FALSE normality |
zero.policy |
default NULL, use global option value; if FALSE stop with error for any empty neighbour sets, if TRUE permit the weights list to be formed with zero-length weights vectors |
spChk |
should the data vector names be checked against the spatial objects for identity integrity, TRUE, or FALSE, default NULL to use |
x |
an object from |
p.adj.method |
correction method as in |
main |
an overall title for the plot |
ylab |
a title for the y axis |
ylim |
the y limits of the plot |
... |
further arguments passed through |
The print function also calculates the standard deviates of Moran's I or Geary's C and a two-sided probability value, optionally using p.adjust
to correct by the nymber of lags. The plot function plots a bar from the estimated Moran's I, or Geary's C value to +/- twice the square root of its variance (in previous releases only once, not twice).
returns a list of class spcor
:
res |
for "corr" a vector of values; for "I", a matrix of estimates of "I", expectations, and variances |
method |
"I" or "corr" |
cardnos |
list of tables of neighbour cardinalities for the lag orders used |
var |
variable name |
Roger Bivand, Roger.Bivand@nhh.no
Cliff, A. D., Ord, J. K. 1981 Spatial processes, Pion, pp. 118–122, Martin, R. L., Oeppen, J. E. 1975 The identification of regional forecasting models using space-time correlation functions, Transactions of the Institute of British Geographers, 66, 95–118.
example(nc.sids) ft.SID74 <- sqrt(1000)*(sqrt(nc.sids$SID74/nc.sids$BIR74) + sqrt((nc.sids$SID74+1)/nc.sids$BIR74)) tr.SIDS74 <- ft.SID74*sqrt(nc.sids$BIR74) cspc <- sp.correlogram(ncCC89_nb, tr.SIDS74, order=8, method="corr", zero.policy=TRUE) print(cspc) plot(cspc) Ispc <- sp.correlogram(ncCC89_nb, tr.SIDS74, order=8, method="I", zero.policy=TRUE) print(Ispc) print(Ispc, "bonferroni") plot(Ispc) Cspc <- sp.correlogram(ncCC89_nb, tr.SIDS74, order=8, method="C", zero.policy=TRUE) print(Cspc) print(Cspc, "bonferroni") plot(Cspc) drop.no.neighs <- !(1:length(ncCC89_nb) %in% which(card(ncCC89_nb) == 0)) sub.ncCC89.nb <- subset(ncCC89_nb, drop.no.neighs) plot(sp.correlogram(sub.ncCC89.nb, subset(tr.SIDS74, drop.no.neighs), order=8, method="corr"))