Randomly select features using Avenue

Summary

The script in this article randomly selects features in a theme.

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 new window:
   
   

   Code:
   theView = av.GetActiveDoc
   theDisplay = theView.GetDisplay
   ThemeList = av.GetActiveDoc.GetActiveThemes
   if (ThemeList.Count <> 1) Then
    msgbox.Error("You must have one and only one active theme",
    "Select Random Sample is aborting")
    exit
   end
   theTheme = ThemeList.Get(0)
   theFtab = theTheme.GetFtab
   theBitMap = theFtab.GetSelection
   theBitMap.ClearAll
   TotalRecs = theFtab.GetNumRecords
   numselect = MsgBox.Input("Enter the Number of Total Population:",
   "Select Random Sample","1")
   
   if ((numselect = NIL) or (numselect.IsNumber.Not)) then exit end
   if((numselect.AsNumber > totalrecs) or (numselect.AsNumber < 1)) then
     Msgbox.Error("You must enter a number between 0 and"
     ++totalrecs.asstring ,"Select Random Sample is aborting")
     exit
   end
   selectnumber = numselect.asnumber
   for each n in 1..selectnumber
     newnumber = Number.MakeRandom ( 0,  totalrecs)
     tf = thebitmap.get(newnumber)
     while (tf.asstring = "true")
       newnumber = number.makerandom(0, totalrecs)
       tf = thebitmap.get(newnumber)
     end
     if (tf.asstring = "false") then
       theBitMap.Set(newnumber)
     else
     end
   end
   
   theDisplay.Invalidate(True)

   
   
3. Attach the script to a button on the View GUI.
   
   
   A. Compile the script.
   B. Switch to the Project window.
   C. Select Customize from the Project menu.
   D. On the Customize dialog box, click the Type dropdown arrow and click View.
   E. Select Buttons under Category.
   F. Click the New button.
   G. Double-click the Click property in the Customize dialog box.
   H. Type the name of the script in the Script Manager and click Select.
   I. Close the Customize dialog box.
   
   For more information, see "Customize dialog box" in ArcView Help.
   
   
4. Open the view and make one theme active.
5. Click the new button.