ascii multicollinearity
Hakim Abdi wrote:
Dear All: I tried searching the r-sig-geo forums regarding this issue but was unable to find a solution. I have a set of variables in ASCII format and I'm trying to see if there's linear inter-correlation amongst some of them. Is there a way in R to assess multicollinearity amongst ASCII grids?
Hi, You can read the asciigrids in to R using rgdal (readGDAL function). A handy way to calculate the linear correlation between the variables is to combine them into a data.frame (where each grid is a long vector, i.e. a column, in the data.frame) and use the cor() function. Do check what assumptions are made when calculating the correlation, for example what the influence is when the data is spatially correlated.
Also, each grid contains 1,919,810 cells and is about ~13-14 MB, so far I have a total of 10 grids, would that be a problem for R? I'm running 2GBs of memory and two Intel dual-core processors @ 1.73GHz each.
doesn't seem like a problem to me, but try and see. cheers, Paul
Thanks for the response. ------------------------------------------------------------------------
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