Hi,
I need some help getting the hypergeom distr. I've started with this code, but it doesn't seem work:
def logchoose(n, k):
lgn = special.gammaln(n+1)
lgk = special.gammaln(k+1)
lgnk = special.gammaln(n-k+1)
return lgn - (lgnk + lgk)
def hypgeo(x, r, b, n):
return exp(logchoose(r, x) + logchoose(b, n-x) - logchoose(r+b, n))
b = 2450
r = 346
N = r + b
n = 5000
x = 1000
p = hypgeo(x,r,b,n)
print p
I think arguments to logchoose() should be swapped
from scipy import exp, special
def logchoose(n, k):
lgn = special.gammaln(n+1)
lgk = special.gammaln(k+1)
lgnk = special.gammaln(n-k+1)
return lgn - (lgnk + lgk)
def hypgeo(x, r, b, n):
u = logchoose(x, r)
v = logchoose(n-x, b)
w = logchoose(n, r + b)
return exp(u + v - w)
b = 2450
r = 346
N = r + b
n = 5000
x = 1000
p = hypgeo(x,r,b,n)
print p
""" my output -->
2.79971621598e-52
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