def PDF(self, x):
if x < 0.0:
return 0.0
else:
if x == 0:
nchoosek = 1.0
elif (x < 0) or (x > self.n):
nchoosek = 0.0
else:
nchoosek = nChooseK(self.n, x)
return nchoosek * pow(self.prob, x) * pow(1.0 - self.prob, self.n - x)
def PDF(self, x): # x is number of white balls drawn
# compute nchoosek(n_white,x)
if x == 0:
nchoosek1 = 1.0
elif (x < 0) or (x > self.n_white):
nchoosek1 = 0.0
else:
nchoosek1 = nChooseK(self.n_white, x)
# compute nchoosek(n_black, n_drawn - x)
if (self.n_drawn - x == 0):
nchoosek2 = 1.0
elif (self.n_drawn - x < 0) or (self.n_drawn - x > self.n_black):
nchoosek2 = 0.0
else:
nchoosek2 = nChooseK(self.n_black, self.n_drawn - x)
# compute nchoosek(n_white + n_black, n_drawn)
if self.n_drawn == 0:
nchoosek3 = 1.0
elif (self.n_drawn < 0) or (self.n_drawn > self.n_white + self.n_black):
nchoosek3 = 0.0
else:
nchoosek3 = nChooseK(self.n_white + self.n_black, self.n_drawn)
# compute
return nchoosek1 * nchoosek2 / nchoosek3
def PDF(self, x):
if (math.isnan(x)):
return float("nan")
elif (self.n == 0.0) and (x == 0.0):
return 1.0
elif (self.n == 0.0) and (x != 0.0):
return 0.0
elif (self.prob == 1.0) and (x != 0.0):
return 0.0
elif (self.prob == 1.0) and (x == 0.0):
return 1.0
elif (x >= 0.0):
if x == 0:
val = 1.0
elif x < 0:
val = 0.0
else:
val = nChooseK(self.n + x - 1.0, x)
return val * pow(1.0 - self.prob, x) * pow(self.prob, self.n)
else:
return 0.0
