Hi
I have two questions concerning the function calc() (more accurately
.calcLayers()) (I append the code of the function below) :
1) The value given to the function fun() is a matrix, containig the values
for many calls from all layers - this is not clear from the help page, and
probably should be changed as it complicates the development of fun()
functions. It effectively assumes, that the function fun() does vectorize
the input parameter, which is in most cases when more complicated
calculations are done, not the case (at least not for me). I would suggest
to put it up to discussion, if this behaviour should be changed.
2) Is the (!canProcessInMemory(x, 2)) correct? I would actually assume, that
the processing in one piece is only done, when canProcessInMemory() is
TRUE?
Cheers and thanks a lot for this really hice package (I am back and using it
again),
Rainer
.calcLayers <- function(x, fun, filename='', ...) {
filename <- trim(filename)
outraster <- brick(x, values=FALSE)
if (!canProcessInMemory(x, 2)) {
v <- t( fun( t( getValues(x) )) )
if (filename != '') {
outraster <- writeRaster(outraster)
}
return( setValues(outraster, v) )
}
if ( filename == '') {
filename <- rasterTmpFile()
}
outraster <- writeStart(outraster, filename=filename, ...)
tr <- blockSize(outraster)
pb <- pbCreate(tr$n, type=.progress(...))
for (i in 1:tr$n) {
sv <- t( fun( t( getValues(x, row=tr$row[i], nrows=tr$nrows[i]) )) )
outraster <- writeValues(outraster, sv, tr$row[i])
pbStep(pb)
}
outraster <- writeStop(outraster)
pbClose(pb)
return(outraster)
}
--
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Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation Biology,
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