Add first/last flag

src/opt_delete.f90

@@ -8,6 +8,7 @@ module opt_delete
     implicit none 
 
     real(kind=dp) :: rc_off
+    logical :: first
 
     public  
     contains
@@ -34,6 +35,7 @@ module opt_delete
         character(len=100) :: textholder
         arg_pos = arg_pos + 1
 
+        first = .true.
         call get_command_argument(arg_pos, textholder, arg_len)
         if(arg_len==0) stop "Missing argument to delete command"
 
@@ -49,6 +51,24 @@ module opt_delete
         end select 
 
         arg_pos = arg_pos + 1
+
+        do while(.true.)
+            if(arg_pos > command_argument_count()) exit
+            !Pull out the next argument which should either be a keyword or an option
+            arg_pos=arg_pos+1
+            call get_command_argument(arg_pos, textholder)
+            textholder=adjustl(textholder)
+
+            select case(trim(textholder))
+            case('first')
+                first=.true.
+            case('last')
+                first=.false.
+            case default
+                !if it isn't an available option to opt_group then we just exit
+                exit 
+            end select
+        end do
     end subroutine parse_delete
 
     subroutine delete_overlap
@@ -99,7 +119,11 @@ module opt_delete
                                     if (norm2(r_atom(:,nei)-r_atom(:,i)) < rc_off) then 
                                         
                                         delete_num = delete_num + 1
-                                        for_delete(delete_num) = max(i,nei)
+                                        if(first) then
+                                            for_delete(delete_num) = min(i,nei)
+                                        else
+                                            for_delete(delete_num) = max(i,nei)
+                                        end if
 
                                         !Now zero out the larger index
                                         if(i < nei) then