lisa {ncf} | R Documentation |
lisa is a function to estimate the local indicators of
spatial association. The function assumes univariate data at each location.
For multivariate data use lisa.nc
lisa(x, y, z, neigh, resamp, latlon, 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 |
vector of n 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. |
quiet |
if TRUE the counter is supressed during execution. |
This is the function to estimate the local indicators of spatial association modified form Anselin (1995). The statistic is the average autocorrelation within a neighborhood.
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 autocorrelation 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 <- rmvn.spa(x=x, y=y, p=2, method="exp") #lisa analysis fit1 <- lisa(x=x, y=y, z=z, neigh=3, resamp=100) ## Not run: plot.lisa(fit1)