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<p class="MsoNormal">Hello,<o:p></o:p></p>
<p class="MsoNormal">I apologize for reposting, but am still confounded after spending more time with the following problem, despite some help from the group.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I am attempting to learn GIS in R. I have worked with ArcGIS a lot, and know that my data is projecting correctly in that environment relative to other trusted data. When I import a text file of animal locations into ArcGIS, then define
the projection as WGS84, then transform to NAD83, I can obtain proj4strings from the resulting shapefiles to use as follows:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">#__________________________________________________________<o:p></o:p></p>
<p class="MsoNormal">#ArcGIS portion---<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">#step 1: bring text file into ArcGIS<o:p></o:p></p>
<p class="MsoNormal">#step 2: display xy events, defining projection as WGS 84<o:p></o:p></p>
<p class="MsoNormal">#step 3: export this data to a shapefile (WGS84)<o:p></o:p></p>
<p class="MsoNormal"># --result: 'bear_ArcGIS_wgs84',<o:p></o:p></p>
<p class="MsoNormal">bear.file.loc<-"c:/dave/temp/rgis"<o:p></o:p></p>
<p class="MsoNormal">bear.wgs84.layer<-"bear_ArcGIS_wgs84"<o:p></o:p></p>
<p class="MsoNormal">bear_wgs84<-readOGR(dsn=bear.file.loc,layer=bear.wgs84.layer)<o:p></o:p></p>
<p class="MsoNormal">string.wgs84<-proj4string(bear_wgs84)<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">#step 4: project this shapefile to NAD83 State Plane AK zone 1<o:p></o:p></p>
<p class="MsoNormal"># --result: 'bear_nad83',<o:p></o:p></p>
<p class="MsoNormal">bear.nad83.layer<-"bear_ArcGIS_nad83"<o:p></o:p></p>
<p class="MsoNormal">bear_nad83<-readOGR(dsn=bear.file.loc,layer=bear.nad83.layer)<o:p></o:p></p>
<p class="MsoNormal">string.nad83.sp.ak.z1<-proj4string(bear_nad83)<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">###check coords...<o:p></o:p></p>
<p class="MsoNormal">coordinates(bear_nad83)<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Then, I would like to ensure that an analogous process in R (via sp and rgdal) works, so I attempt this, using the proj4strings from above:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">#__________________________________________________________<o:p></o:p></p>
<p class="MsoNormal">#R portion---<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">#step 1: read table into R<o:p></o:p></p>
<p class="MsoNormal">txt.loc<-"C:/dave/temp/rgis/bear.txt"<o:p></o:p></p>
<p class="MsoNormal">bear.via.R.wgs84<-read.table(txt.loc,header=T,sep=",",stringsAsFactors=F)<o:p></o:p></p>
<p class="MsoNormal">#step 2: define coordinate columns<o:p></o:p></p>
<p class="MsoNormal">#coordinates(bear.via.R.wgs84)<-c("Long_","Latitude")<o:p></o:p></p>
<p class="MsoNormal">coordinates(bear.via.R.wgs84)<- ~Long_ + Latitude<o:p></o:p></p>
<p class="MsoNormal">#step 3: define projection<o:p></o:p></p>
<p class="MsoNormal">proj4string(bear.via.R.wgs84)<-string.wgs84<o:p></o:p></p>
<p class="MsoNormal">writeOGR(bear.via.R.wgs84,dsn=bear.file.loc,layer="bear_R_wgs84",<o:p></o:p></p>
<p class="MsoNormal"> driver=ogrDrivers()[7,1])<o:p></o:p></p>
<p class="MsoNormal">bear.via.R.nad83<-spTransform(bear.via.R.wgs84,CRS(string.nad83.sp.ak.z1))<o:p></o:p></p>
<p class="MsoNormal">proj4string(bear.via.R.nad83)<o:p></o:p></p>
<p class="MsoNormal">writeOGR(bear.via.R.nad83,dsn=bear.file.loc,layer="bear_R_nad83",<o:p></o:p></p>
<p class="MsoNormal"> driver=ogrDrivers()[7,1])<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">###check coords...<o:p></o:p></p>
<p class="MsoNormal">coordinates(bear.via.R.nad83)<o:p></o:p></p>
<p class="MsoNormal">#__________________________________________________________<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">As you can see if you are saintly enough to still be with me, the coordinates do not jive. I attach the animal locations I am working with in case there is someone who wants to try to replicate the process. I am also attaching the shapefiles
generated by ArcGIS and by R in case they are useful to you.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks so much for your time. <o:p></o:p></p>
<p class="MsoNormal">__________________________________<o:p></o:p></p>
<p class="MsoNormal">Dave Gregovich<o:p></o:p></p>
<p class="MsoNormal">Research Analyst<o:p></o:p></p>
<p class="MsoNormal">Alaska Department of Fish and Game<o:p></o:p></p>
<p class="MsoNormal">Wildlife Conservation Division<o:p></o:p></p>
<p class="MsoNormal">Douglas, AK 99821<o:p></o:p></p>
<p class="MsoNormal">(907) 465-4291<o:p></o:p></p>
<p class="MsoNormal">dave.gregovich@alaska.gov<o:p></o:p></p>
<p class="MsoNormal">__________________________________<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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