lisa.nc {ncf} | R Documentation |
lisa.nc is a function to estimate the (noncentred) local indicators of
spatial association. The function requires multiple observations at each location.
For single observations at each location use lisa
lisa.nc(x, y, z, neigh, na.rm = FALSE, resamp=1000, latlon = FALSE, quiet = FALSE)
x |
vector of length n representing the x coordinates (or latitude; see latlon). |
y |
vector of length n representing the y coordinates (or longitude). |
z |
a matrix of dimension n x p representing p (>1) observation at each location. |
neigh |
neighborhood size. |
resamp |
number of resamples under the NULL to generate p-values |
latlon |
Not yet implemented: if TRUE, coordinates are latitude and longitude. |
na.rm |
if TRUE, NA's will be dealt with through pairwise deletion of missing values. |
quiet |
if TRUE the counter is supressed during execution. |
This is the function to estimate the (non-centered) local indicators of spatial association modified form Anselin (1995). 'correlation' is the average correlation within a neighborhood. The function requires multiple observations at each location.
Missing values are allowed – values are assumed missing at random.
An object of class "lisa" is returned, consisting of the following components:
n |
the number of pairs within each neighborhood. |
dmean |
the actual mean of distance within each neighborhood. |
correlation |
the mean correlation within the neighborhood (neigh). |
p |
the permutation two-sided p-value for each distance-class. |
coord |
a list with the x and y coordinates. |
Ottar N. Bjornstad onb1@psu.edu
Anselin, L. 1995. Local indicators of spatial association - LISA. Geographical Analysis 27:93-115.
#first generate some sample data x <- expand.grid(1:20, 1:5)[,1] y <- expand.grid(1:20, 1:5)[,2] #z data from an exponential random field z <- cbind( rmvn.spa(x=x, y=y, p=2, method="exp"), rmvn.spa(x=x, y=y, p=2, method="exp") ) #lisa.nc analysis fit1 <- lisa.nc(x=x, y=y, z=z, neigh=3) ## Not run: plot.lisa(fit1)