Skip to content

Binary Map File

4 messages · Iqbal Jamal, Roger Bivand

Original
2 days later
Roger Bivand
#
On Mon, 26 Nov 2007, Iqbal Jamal wrote:

            

      
      
      
    

        
It seems possible that the boundaries you want may be found on the WMS 
service at http://www.geobase.ca/geobase/en/index.html, but a WFS service 
would have been more use. There may be other sources - could anyone with 
insight into boundary data for counties in Alberta, presumably as vector 
polygons, please help?

I'm not sure what is meant by a binary map here - digital?

Roger

            

      
      
      
    

        

      
      
    

        

  
    

      
      
    

  


  


      

    

    

      
      

        
      

    

    

      
      

        


  

        

      Roger Bivand
    

    

      
      #
    

  


  

      
On Wed, 28 Nov 2007, Iqbal Jamal wrote:

        

            

      
      
      
    

        
You can go that way if you choose. You'll need first to break out the line 
segments into a text file, then massage them manually into the required 
unique format. They will then need to have their topologies built, and as 
a final exercise in patience, you'll need to find out which built polygons 
belong to which counties. All of this is described in:

Richard A. Becker, and Allan R. Wilks, "Constructing a Geographical 
Database", AT&T Bell Laboratories Statistics, Research Report [95.2], 
1995. http://public.research.att.com/areas/stat/doc/95.2.ps

as mentioned in ?map.

On the other hand, you might find it easier to read the boundary data file 
by functions in the rgdal, maptools, shapefiles, or RArcInfo packages, 
read it in, and use it directly? The difference is mostly that map() style 
polygons must have a built topology because the line segments are only 
stored once, while most external formats and there representations in R 
(such as the sp package SpatialPolygons class) use a list of closed rings, 
avoiding building topologies.

Usually, finding the data file is the most difficult, and you'll need it 
anyway irrespective of your choice.

Roger