gdistance resistanceDistance error
Dear Jacob, Hope you don't mind if I don't write in the post but directly to you. Actually, as you might suppose, the data is too heavy in order for me to send it. However, I will summ it up: the data is a grid of the American continent with a ~0.05x0.05 degree resolution and values that correspond to the probability of presence (ranging from ~1.5e-7 to ~0.9). There are more than 5000000 cells, but about 2/3 are NA's (is this what is causing the trouble?) I have looked how to remove this NA cells without success (when I rasterize the points, the grid automatically adds a rectangular grid with NAs where no data is found). Any help would be most appreciated, Best Ignacio
On May 8, 2012, at 6:54 PM, Jacob van Etten [via R-sig-geo] wrote:
Dear Ignacio, The problem may also have to do with the values in the TransitionMatrix. A reproducible example would be good to have. Jacob On 8/05/2012, at 18:32, "ignacio.quintero" <[hidden email]> wrote:
Dear all, I have came across the same error using resistanceDistance (and not costDistance with same data): "#Get matrix of resistance distances. Error in Cholesky(Lr) : CHOLMOD factorization was unsuccessful In addition: Warning message: In Cholesky(Lr) : Cholmod warning 'not positive definite' at file:../Cholesky/t_cholmod_rowfac.c, line 432" I was using also a very large raster grid (~5000000 cells). This seems to be the problem (do not know if because of memory): I cropped the same big raster into a smaller one containing the locality points (and, of course, a big frame outside; however, currently, I do not know if the frame extent will change the results...) and it worked perfectly. Hope this helps (although I would like to know the exact problem (memory or other issue) with the resistanceDistance function) Best, Ignacio -- View this message in context: http://r-sig-geo.2731867.n2.nabble.com/gdistance-resistanceDistance-error-tp7076485p7541017.html Sent from the R-sig-geo mailing list archive at Nabble.com.
_______________________________________________ R-sig-Geo mailing list [hidden email] https://stat.ethz.ch/mailman/listinfo/r-sig-geo
_______________________________________________ R-sig-Geo mailing list [hidden email] https://stat.ethz.ch/mailman/listinfo/r-sig-geo If you reply to this email, your message will be added to the discussion below: http://r-sig-geo.2731867.n2.nabble.com/gdistance-resistanceDistance-error-tp7076485p7541075.html To unsubscribe from gdistance resistanceDistance error, click here. NAML
-- View this message in context: http://r-sig-geo.2731867.n2.nabble.com/gdistance-resistanceDistance-error-tp7076485p7541430.html Sent from the R-sig-geo mailing list archive at Nabble.com.