Traceback (most recent call last):

  File "C:\Python26\lib\site-packages\django\core\servers\basehttp.py", line 279, in run
    self.result = application(self.environ, self.start_response)

  File "C:\Python26\lib\site-packages\django\core\servers\basehttp.py", line 651, in __call__
    return self.application(environ, start_response)

  File "C:\Python26\lib\site-packages\django\core\handlers\wsgi.py", line 241, in __call__
    response = self.get_response(request)

  File "C:\Python26\lib\site-packages\django\core\handlers\base.py", line 134, in get_response
    return self.handle_uncaught_exception(request, resolver, exc_info)

  File "C:\Python26\lib\site-packages\django\core\handlers\base.py", line 154, in handle_uncaught_exception
    return debug.technical_500_response(request, *exc_info)

  File "C:\Python26\lib\site-packages\django\views\debug.py", line 40, in technical_500_response
    html = reporter.get_traceback_html()

  File "C:\Python26\lib\site-packages\django\views\debug.py", line 86, in get_traceback_html
    frames = self.get_traceback_frames()

  File "C:\Python26\lib\site-packages\django\views\debug.py", line 205, in get_traceback_frames
    pre_context_lineno, pre_context, context_line, post_context = self._get_lines_from_file(filename, lineno, 7, loader, module_name)

  File "C:\Python26\lib\site-packages\django\views\debug.py", line 186, in _get_lines_from_file
    context_line = source[lineno].strip('\n')

IndexError: list index out of range

Totally mysterious: there is not a line of my code in the trace stack and I have no idea what file it is trying to index into. I really made no progress on this until I tried the shell:

>>> from django_league.league.models import *
>>> Sport.objects.create(sport_name='Hockey')
__unicode__
Traceback (most recent call last):
  File "lgt;console>", line 1, in lgt;module>
  File "C:\Python26\lib\site-packages\django\db\models\base.py", line 328, in __
repr__
    u = unicode(self)
  File "C:\Users\hughdbrown\Documents\django\django_league\..\django_league\leag
ue\models.py", line 17, in __unicode__
    return u"%s" % (sport_name, )
NameError: global name 'sport_name' is not defined

Now we're getting somewhere, I thought. I have a function of mine in scope. The problem was that I had defined my __unicode__ method without using self in the code:

class Sport(models.Model):    
    sport_name = models.CharField(max_length=20)
    def __unicode__(self):
        return u"%s" % (self.sport_name, )

    @models.permalink
    def get_absolute_url(self):
        return ('sport', None, {'object_id' : self.id})

    class Meta:
        ordering = ['sport_name']

So fixing it was pretty easy once I knew that.

Public Class ReversedComparer(Of T As IComparable)
    Implements IComparer(Of T)
    Public Function Compare(ByVal x As T, ByVal y As T) As Integer _
    Implements System.Collections.Generic.IComparer(Of T).Compare
       Return -x.CompareTo(y)
    End Function
End Class

Private Shared Function BinarySearch(Of T As IComparable)(ByRef x() As T, _
                                     ByVal val As T, _
                                     ByVal comparer As IComparer(Of T)) As Integer
    Dim lo As Integer = 0, hi As Integer = x.Count - 1
    While lo <= hi
        Dim mid As Integer = (hi + lo) \ 2
        If comparer.Compare(val, x(mid)) <> 1 Then
            hi = mid - 1
        Else
            lo = mid + 1
        End If
    End While
    Return CInt(If(comparer.Compare(x(lo), val) = 0, lo, -1))
End Function

Public Shared Function Rank(ByRef X() As Double) As Integer()
    Dim sorted() As Double = (From xx In X Order By xx Descending Select xx).ToArray()
     Dim comparer As IComparer(Of Double) = New ReversedComparer(Of Double)
     Return X.Select(Function(val) 1 + BinarySearch(Of Double)(sorted, val, comparer)).ToArray()
End Function

And it's pretty good as far as it goes. It takes a copy of the data in reverse-sorted order and then does a binary search to find the 0-based position in the array for each element in the original array. And that's fine, but I wanted to implement something more like my python code:

import collections
def rank(arr):
	"""
	>>> a = list(range(10))
	>>> print rank(a)
	[10, 9, 8, 7, 6, 5, 4, 3, 2, 1]
	>>> b = list(range(10))
	>>> b.reverse()
	>>> print rank(b)
	[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
	>>> c = [5] * 10
	>>> print rank(c)
	[1, 1, 1, 1, 1, 1, 1, 1, 1, 1]
	>>> d = ([5] * 5) + ([1] * 5)
	>>> d
	[5, 5, 5, 5, 5, 1, 1, 1, 1, 1]
	>>> print rank(d)
	[1, 1, 1, 1, 1, 6, 6, 6, 6, 6]
	"""
	d = collections.defaultdict(list)
	for i, v in enumerate(arr):
		d[v].append(i)
	result = [0] * len(arr)
	i = 1
	for k in sorted(d, reverse = True):
		for j in d[k]:
			result[j] = i
		i += len(d[k])
	return result

if __name__ == '__main__':
	import doctest
	doctest.testmod()
 

So I worked through the LINQ issues using the LinqPad interpreter and came up with this:

Function Rank(Of T)(Byref x() as T) as Integer()
    Dim original_pos = x.Select(Function(xx, index) New With {.Val = xx, .Index = index}) _
             .ToLookup(Function(xxx) xxx.Val)
    Dim keys = original_pos.OrderByDescending(Function(yy) yy.Key)    
    Dim result(x.Count-1) as Integer
    Dim i as Integer = 1
    For Each item in keys
        For Each v in item
            result(v.Index) = i
        Next
        i = i + item.Count
    Next
    Return result
End Function

And I think that's pretty good code: templatized LINQ code that uses lambda functions and implements the algorithm as quickly as I know how.