[R-sig-Geo] Help with ENFA in R

[JonathanAronson]

Hi Clement

Thank you very much for your input. I have read the maptools information and
seen the examples for readAsciiGrid. I would like to create a
SpatailPixelDataFrame which contains the raster maps of 15 environmental
variables. Therefore, similar to the lynxjura$map SpatailPixelDataFramewhich
contains 4 environmental variables. How did you create the lynxjura$map data
frame - can you please show me step by step? You suggested using the
readAsciiGrid function to import my maps. Is this how I can create the
SpatailPixelDataFrame with the 15 variables I need? I do not understand the
example code to do this (I am new to R): 

x <- readAsciiGrid(system.file("grids/test.ag", package="maptools")[1])
summary(x)
image(x)
xp <- as(x, "SpatialPixelsDataFrame")
abline(h=332000, lwd=3)
xpS <- xp[coordinates(xp)[,2] < 332000,]
summary(xpS)
xS <- as(xpS, "SpatialGridDataFrame")
summary(xS)
tmpfl <- paste(tempdir(), "testS.ag", sep="/")
writeAsciiGrid(xS, tmpfl)
axS <- readAsciiGrid(tmpfl)
opar <- par(mfrow=c(1,2))
image(xS, main="before export")
image(axS, main="after import")
par(opar)
unlink(tmpfl)

Thanks in advance
Jonathan



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