[R] Simulating a landscape (matrix) in R
vicgrave at hotmail.com
Thu Jun 3 23:38:08 CEST 2004
You could try something like this.
Simulating with a large number of grid cells is however very RAM expensive.
x <- expand.grid(1:30, 1:30)
distances <- as.matrix(dist(x, diag=T, upper=T))
Sigma <- expcov(r=distances, d=10, se=1)
z <- mvrnorm(n = 1, mu=rep(0,900), Sigma)
z <- matrix(z,nrow=30)
----- Original Message -----
From: "Brian Davenhall" <bdavenhall at sbcglobal.net>
To: <r-help at stat.math.ethz.ch>
Sent: Thursday, June 03, 2004 10:46 PM
Subject: [R] Simulating a landscape (matrix) in R
> I'm trying to figure out how one might go about simulating a landscape
> (matrix) in R. For example if one wanted to generate a simulated landscape
> of precipitation values for some area (say a 100 X 100 matrix) they could
> generate 10,000 numbers using a random normal distribution with a mean and
> std. dev. and randomly allocate these generated numbers to the grid cells.
> However, this is too simplistic and the resulting matrix will be very noisy
> since one cell could have a very high value and an adjacent cell could have
> a very low value. Is it possible to generate a simulated matrix that would
> somehow incorporate a measure of spatial autocorrelation, so that grid cells
> closer to each other are similar?
> Is this sort of thing possible in R to get a realistic surface or are other
> software packages (e.g., surface visualizations/rendering) more appropriate
> for this sort of thing?
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