QW Scripting: Sortlist

Sortlist

Sortlist is a subroutine that sorts a list of simple elements. Simple elements are the built-in datatypes of QSL. For example numbers or strings. The script uses a heapsort algorithm, which should have reasonably good performance, even for quite large lists. Information on sortlist is organized as follows:

Parameters
Result
Sorting Numbers
Sorting Strings
Performance

Sortlist Parameters

There are two parameters to the sortlist subroutine:

list: This is a required parameter. It is a standard QSL list with one or more elements. The original list passed into sortlist is never changed (see the result below).
ascending: This is an optional parameter. Pass true for ascending sort sequence and false for descending. If the parameter is omitted, ascending is assumed.

Sortlist Result

The return value of sortlist is the original list in sorted order.

Sorting Numbers

The following provides an example of sorting a short list of numbers:

	list = {5, 9, 1, 8, 2};
	
	result = dialog("Before " + string(list));

	sortedlist = sortlist(list, true);

	result = dialog("After " + string(sortedlist));

Sorting Strings

The following provides an example of sorting a short list of strings. In this case each string is only a single character long. We also ask the the resulting list be in descending sequence:

	list = {"f", "b", "a", "e", "d"};
	
	result = dialog("Before " + string(list));

	sortedlist = sortlist(list, false);

	result = dialog("After " + string(sortedlist));

Performance

To test the performance of sortlist we created a test subroutine. This subroutine creates the list in ascending sequence and then requests that the list be sorted in descending sequence.

sub performancetest(count)

	list = {};
	
	repeat for inx from 1 to count
	
		list = list + inx;
		
	endrepeat
	
	result = dialog("list ready to sort");
	
	list = sortlist(list, false);
	
	result = dialog("list sorted");
	
	finished = false;
	inx      = 1;
	
	repeat while not finished
		if list[inx] < list[inx + 1] then
			msg = "List not sorted at ";
			msg = msg + "list[";
			msg = msg + string(inx);
			msg = msg + "] = ";
			msg = msg + string(list[inx]);
			msg = msg + " list[";
			msg = msg + string(inx + 1);
			msg = msg + "] = ";
			msg = msg + string(list[inx + 1]);
			result = dialog(msg);
			finished = true;
		else
			inx = inx + 1;
			if inx >= count then
				finished = true;
			endif
		endif
	endrepeat
	
endsub	

	performancetest(250);

The timing results were calculated from when the sort started until when the sort ended. The performance results using a preliminary retail build of QW 4.7.06 were as follows:

Date: February 22, 1999 at 5:55 PM (Pacific)
Person: David
Machine: Vectra XU
CPU: Dual Pentium 133
Memory: 128 MB
OS: WinNT 4.0 SP3
Timing: 18 elapsed seconds for 250 entries

Date: February 22, 1999 at 8:00 PM (Mountain)
Person: Neil
Machine: Dell Dimension xps D300
CPU: Pentium II 300 Mhz
Memory: 64 MB
OS: WinNT 4.0 SP3
Timing: 6 elapsed seconds for 250 entries

Date:	February 22, 1999 at 5:55 PM (Pacific)
Person:	David
Machine:	Vectra XU
CPU:	Dual Pentium 133
Memory:	128 MB
OS:	WinNT 4.0 SP3
Timing:	18 elapsed seconds for 250 entries

Date:	February 22, 1999 at 8:00 PM (Mountain)
Person:	Neil
Machine:	Dell Dimension xps D300
CPU:	Pentium II 300 Mhz
Memory:	64 MB
OS:	WinNT 4.0 SP3
Timing:	6 elapsed seconds for 250 entries