I would suggest asking this on R-sig-geo. https://stat.ethz.ch/mailman/listinfo/r-sig-geo --------------------------------------------------------------------------- Jeff Newmiller The ..... ..... Go Live... DCN:<jdnew...@dcn.davis.ca.us> Basics: ##.#. ##.#. Live Go... Live: OO#.. Dead: OO#.. Playing Research Engineer (Solar/Batteries O.O#. #.O#. with /Software/Embedded Controllers) .OO#. .OO#. rocks...1k --------------------------------------------------------------------------- Sent from my phone. Please excuse my brevity.
Mike Bock <mb...@environcorp.com> wrote: >I am working with spatial data in ggmap, generally with great success. >I have a huge data set with the coordinates in NAD 83 UTM Zone 11 >(meters). To map the data the coordinates were converted to Lat Long >in GIS prior to use in R and ggmap/ggplot. I am using hexagonal binning >to aggregate the data : >#create bins and calculate stats > >hb<-hexbin(DF$lon,DF$lat,xbins=80,IDs=TRUE) >hb.avg<-hexTapply(hb,DF$Res,mean,na.rm=TRUE) >hb.mx<-hexTapply(hb,DF$Res,max,na.rm=TRUE) >hb.p80<-hexTapply(hb,DF$Res,quantile,prob=0.80,na.rm=TRUE) >#create df for ggplot >hx_dat <- data.frame(hcell2xy(hb), count = hb@count, > xo = hb@xcm, yo = hb@ycm, Mean=hb.avg,Max=hb.mx, > p80=hb.p80) > >#Base Map >#BBox is the bounding box >Base<-get_map(BBox,source='google') >m_hx<-ggmap(Base,legend = "bottom", >base_layer=ggplot(aes(x=x,y=y),data=hx_dat)) >#Map of means >a<-0.55 >hc<-'grey60' > >m_hx+geom_hex(aes(x = x, y = y, fill = Mean), > color = hc, ,alpha=a,stat = "identity") + > scale_fill_gradientn("Mean",colours=rev(rainbow(4)),trans='sqrt') > >...and so on for other stats >I can also run statistical analyses on hx_dat. >By creating hexbins based on lat/long it seems there will be distortion >due to the differences in length of a degree at different locations on >the earth's surface. What is the most efficient way to eliminate this >distortion? Should I run hexbin in NAD83 and convert the x/y >coordinates to Lat Long? Can I get ggmap to convert the baselayer to >NAD84 and just do everything in NAD(my preferred option)? >I have tried converting Lat Long to NAD84 and back but the coordinates >are coming up in the eastern Pacific and not in California, so I am >missing something and I am not sure that is the best way to solve the >problem anyway. Thanks in advance, any help is greatly appreciated >Mike > >Michael J. Bock, PhD | Senior Manager >mb...@environcorp.com > > > > > > >________________________________ >This message contains information that may be >confidenti...{{dropped:8}} > >______________________________________________ >R-help@r-project.org mailing list >https://stat.ethz.ch/mailman/listinfo/r-help >PLEASE do read the posting guide >http://www.R-project.org/posting-guide.html >and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.