Convert polygons or polylines into line segments

Summary

The script in this article takes a polygon or polyline theme and break it into a line theme with a separate feature for each line segment.

Procedure

1. Open a new script window.
   
   
   A. Activate the Project window.
   B. Click the Scripts icon.
   C. Click New.
   
   
2. Copy the following code into the script window:
   
   

   Code:
   '-- Pgn2Line.ave
   
   '-- This script takes a polygon or polyline theme and
   '-- extracts each individual line segment between vertices.
   '-- The list of these line segments is used to create a 
   '-- new line theme.
   
   theView=av.getactivedoc
   theTheme=theView.getactivethemes.get(0)
   theFtab=theTheme.getftab
   theFtabCount=theFtab.getnumrecords
   thesf=theFtab.FindField("Shape")
   theNewLOL={}
   
   for each r in theftab
     av.ShowMsg("Counting line segments...")
     av.SetStatus(((r+1)/theFtabCount) * 100)
     thePg=theftab.returnvalue(thesf,r)
     theNewLOP={}
     theLOLOP=thePG.aslist
       for each l in theLOLOP
         theLOP=l.aslist
           for each thept in theLOP
             theNewLOP.Add(thept)
           end  
       end
     theNewLOPcount=theNewLOP.Count 
     pt1i=0
     pt2i=1
     for each apt in 2..theNewLOPcount
       pt1=theNewLOP.Get(pt1i)
       pt2=theNewLOP.Get(pt2i)
       theNewLine=Line.Make(pt1, pt2)
       theNewLOL.Add(theNewLine)
       pt1i=pt1i+1
       pt2i=pt2i+1
     end  
   end 
   
   av.clearmsg
   av.clearstatus
   
   '-- Make the new polyline shapefile   
   
   theNewLOLcount=theNewLOL.Count.asstring
   msgbox.info("The line theme will have"++theNewLOLcount++"lines in it","Almost done")
   
   out_name = FileDialog.Put( "*.shp".asfilename, "*.shp", "Output Shapefile")
   
   if (out_name = nil) then
     exit
   end
    
   myidfld = Field.Make("myID",#FIELD_LONG,6,0)
   fields  = List.Make
   Fields.Add(myIDfld)
   tblrecno=0
   
   '-- Create the new Ftab and add fields 
   
     tbl = Ftab.MakeNew( out_name, Polyline )
     tbl.AddFields( fields )
   
   '-- Add the records, ID value, and polyline to the ftab
   
   for each npl in 0..(theNewLOL.count-1)
     av.showmsg("Creating new shapefile"++out_name.asstring++"...")
     av.setstatus(((npl+1)/theNewLOLcount.asnumber) *100)
     tbl.addrecord
     tbl.SetValue(myIDfld, npl, npl) 
     tbl.SetValue(tbl.FindField("Shape"), npl, theNewLOL.Get(npl).aspolyline) 
   end
   
   theNewFtheme=Ftheme.Make(tbl)
   theView.AddTheme(theNewfTheme)
   theNewFtheme.SetVisible(true)
   theNewFtheme.SetActive(true)
   thetheme.SetVisible(false)
   thetheme.setactive(false)
   theview.Invalidate
   av.clearmsg
   av.clearstatus
   msgbox.Info("Finished!","")
   

   
   
3. Click the Compile button.
   
   
4. Make the view and theme active.
5. Click the script window.
6. Click the Run button.
   
   

   Note:
   This script will not work with island polygons.