SpreadTooThin wrote: > I have a list and I need to do a custom sort on it... > > for example: > a = [1,2,3,4,5,6,7,8,9,10] #Although not necessarily in order > > def cmp(i,j): #to be defined in this thread. > > a.sort(cmp) > > print a > [1,4,7,10, 2,5,8, 3,6,9] > > So withouth making this into an IQ test. > Its more like > 1 4 7 10 > 2 5 8 > 3 6 9 > > Read that top to bottom from column 1 to column 4. > When you get to the bottom of a column move to the next column. > Get it? It's a little vague, but i'm supposing that if you have an 11 in a the order will be: [1,4,7,10, 2,5,8,11, 3, 6,9] If this holds then your order is based on x%3. You place first all x for which x%3 == 1, then x%3 == 2, and last x%3 == 0. And among these three group you use "natural" order. so: def yourcmp(i,j): ri = i%3 rj = j%3 if ri == rj: return i.__cmp__(j) elif ri == 0: return 1 elif rj == 0: return -1 else: return ri.__cmp__(rj) This works with your example, and with my assumption, feel free to "optimize" the if/elif block.
However you shuold pay attention to the 0 behavior. a = range(11) a.sort(yourcmp) print a [1, 4, 7, 10, 2, 5, 8, 0, 3, 6, 9] -- http://mail.python.org/mailman/listinfo/python-list
