[Tutor] Is there a better way to do this? (original) (raw)

Jeff Shannon jeff at ccvcorp.com
Thu Jul 22 23:40:54 CEST 2004


Hee-Seng Kye wrote:

I'm trying to write a program that computes six-digit numbers, in which the left digit is always smaller than its following digit (i.e., it's always ascending). The output of the program starts with "0 1 2 3 4 5" and ends on "6 7 8 9 A B." The best I could do was to have many embedded 'for' statements:

c = 1 for p0 in range(0, 7): for p1 in range(1, 12): for p2 in range(2, 12): for p3 in range(3, 12): for p4 in range(4, 12): for p5 in range(5, 12): if p0 < p1 < p2 < p3 < p4 < p5: print repr(c).rjust(3), "\t", print "%X %X %X %X %X %X" % (p0, p1, p2, p3, p4, p5) c += 1 print "...Done"

I don't have the time / spare brain cycles to write real sample code, but if I were doing something like this, I'd look closely at the possibility of using a recursion instead of multiply-nested for loops. You might be able to craft a recursive generator that would iterate over its sub-generator and then itself. I don't know whether this would be likely to run faster, but it would be a lot more flexible than manually writing out N levels of for-loops...

def my_generator(depth, min, max): for n in range(min, max): for result in my_generator(depth-1, n, max): yield (n,) + result

for results in my_generator(depth, min, max): format = " ".join(["%X"] * depth) print format % results

The generator there won't actually work -- it needs to do bounds-checking on depth before entering the loop, and of course I haven't tested any of this -- but this may give you a starting point.

Jeff Shannon Technician/Programmer Credit International



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