Dick Moores wrote:
> Paul Rubin's fencepost method is about 14 times faster than mine for
> the same M == 8 and N == 4! :(
Actually they looked a bit similar after I had mucked a bit with them
:-) But indeed it's slow.
> Sorry, I don't understand this. Could you spell it out for me by
> rewriting my above test to use it? Thanks!
OK here you go. I'm copying a modification from something that I used to
check something else, I hope you recognize the code after my refactoring.
from itertools import islice
import random
def sumRndInt(m,n):
while 1:
L = [random.randint(1,m-n+1) for i in xrange(n)]
if sum(L) == m:
yield tuple(L)
def fencepost(m,n):
while 1:
t = sorted(random.sample(xrange(1,m), n-1))
yield tuple((j-i) for i,j in zip([0]+t, t+[m]))
def freq(g,k):
D = {}
for x in islice(g,k):
D[x] = D.get(x,0)+1
return D
def test():
m = 7
n = 4
k = 20000
R = freq(sumRndInt(m,n),k)
F = freq(fencepost(m,n),k)
assert sorted(R) == sorted(F)
for x in sorted(R):
print x,R[x],F[x]
if __name__=='__main__':
test()
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