Dear all, I a read with great interest the e-mails related to Arnav Sheth about memory limitation when computing a distance matrix. I suspect that I will also meet some memory limitation using GeoR. I am currently running GeoR on a geodata object including 2686 geographical coordinates. krige.conv() can handle it (it takes 10-15 mn of computing) but requests an increased memory.> memory.limit(size=500000000)When the computing is completed, the computer speed is considerably slowed down for any application. It is thus most necessary to shut it down and restart. I will probably have to handle a set of 5000-6000 coordinates in once in the next few months. I wonder if it will go through it on my plateform (Windows XP and compaq nx7000). If not, will the limitation due to R or to Windows? Does an alternate solution exist? Thanks for any hint, Patrick Giraudoux
Usually, with that many observations, you use kriging in a local neighbourhood, i.e. use only the n nearest observations in a kriging system. If n is pretty large, this is practically equivalent to kriging with a global neighbourhood. There are several other R packages that provide kriging, some of which provide local kriging, e.g. gstat does not require calculation of the full distance matrix. -- Edzer