I am tracking a variable number of walruses throughout their summering range in the Chukchi Sea. We wish to summarize monthly summer foraging home ranges based on daily locations and a daily summary of foraging behavior measured by instruments on-board the satellite-linked tag, which is a metric similar in nature to the 'activity' index utilized by Benhamou and Cornelis (2010).
For each walrus with a threshold amount of tracking in each month I construct a utilization distribution. Then I must exclude land as non-habitat from each walruses monthly utilization distribution. Because their summering range abuts a coastline that is too complex (sharp peninsulas and sounds that violate the angle rules and relatively short shore line segments that violate the 3*h rule of Benhamou and Cornelis (2010)) the BRB(boundary=simpleCoastLine) option fails. As such, I am inclined to resort to the raster exclusion approach, whereby a pre-constructed raster with cell values assigned to 1 (habitat) or 0 (non-habitat) is multiplied against each utilization distribution, all built on the same raster grid. Under the predecessor package, adehabitat, I would multiply each estimated utilization distribution (class asc) by a raster (also of class asc, read in using the rgdal readGDAL() function). Please advise on how to multiply out the non-habitat from the estUDm class object and how to normalize total volume back to 1. Also, please advise on how to summarize utilization distributions across walruses (in each estUDm object) to derive a single generalized utilization distribution for each month. ----- Tony Fischbach, Wildlife Biologist Walrus Research Program Alaska Science Center U.S. Geological Survey 4210 University Drive Anchorage, AK 99508-4650 afischb...@usgs.gov http://alaska.usgs.gov/science/biology/walrus -- View this message in context: http://r-sig-geo.2731867.n2.nabble.com/Walruses-and-adehabitatHR-class-estUDm-exclusion-of-non-habitat-pixels-and-summary-over-all-animals-tp6497315p6497315.html Sent from the R-sig-geo mailing list archive at Nabble.com. _______________________________________________ R-sig-Geo mailing list R-sig-Geo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo