stgmix | R Documentation |
Generates a pixel image array of a specified trivariate normal mixture density observed on a bounded window in space and time.
stgmix(mean, vcv, window, tlim, p0 = 0, p = NULL, sres = 128, tres = sres, int = 1)
mean |
A 3 x N matrix specifying the means of each of N contributing normal densities; each component in the order of (x-coord, y-coord, time-coord). |
vcv |
A 3 x 3 x N array specifying the variance-covariance matrices of each contributing density. |
window |
An object of class |
tlim |
A vector of length 2 giving the boundaries of the time interval on which the mixture density is defined. |
p0 |
The proportion of uniform density that contributes to the final mixture (default is 0). |
p |
A numeric vector of the N proportions for each contributing density (default is equal proportions for each density, after subtracting |
sres |
The spatial resolution (number of pixels) along each side of the spatial grid (default is 128). |
tres |
The temporal resolution (default is to equate with |
int |
A positive numeric value for post-hoc rescaling of the density (useful if the user wishes to return a spatiotemporal intensity function). Defaults to 1 for no change in scaling. |
This function creates a 3D array of a density function made up of a mixture of N trivariate normals with the interpretation of a continuous probability density function in space-time. As such, each component is restricted to conserve mass over a 3D region specified by a fixed polygonal window
in space, stretched over defined temporal limits (tlim
). A warning will appear if less than 1% of the integral of each Gaussian bump is inside this observational spatiotemporal polyhedron.
An object of class stim
giving the trivariate density. This is a list with six components:
a |
The |
v |
A pixel |
xcol |
Grid coordinates in the spatial x-axis (corresponds to each spatial |
yrow |
Grid coordinates in the spatial y-axis (corresponds to each spatial |
tlay |
Grid coordinates in the temporal axis (corresponds to the order of the spatial |
W |
A copy of |
A.K. Redmond and T.M. Davies
require("abind") m1 <- c(0.3,0.3,2) m2 <- c(0.5,0.8,8) m3 <- c(0.7,0.6,7) v1 <- diag(c(0.01^2,0.01^2,1)) v2 <- diag(c(0.005,0.005,0.5)) v3 <- diag(c(0.005,0.005,0.5)) stg1 <- stgmix(mean=cbind(m1,m2,m3), vcv=abind(v1,v2,v3,along=3), window=toywin,tlim=c(1,10), p0=0.1,tres=64) plot(stg1,log=TRUE) mn <- matrix(c(0,0,0,-2,1,4,1,-2,8),nrow=3) vr <- array(c(1,0,0,0,1,0,0,0,1,1,0,0.5,0,1,0,0.5,0,3,1,0,0,0,2,0,0,0,1), dim=c(3,3,3)) stg2 <- stgmix(mean=mn,vcv=vr,window=shp1, tlim=c(0,10),tres=50) plot(stg2,fix.range=TRUE,sleep=0.1)
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