I mean to define the following recursive function
But I don't know what goes wrong in my code. May anyone more experienced with Python take a look into that? Thank you!
import scipy.special
def F(n,k):
if (k == 1):
F = 1
else:
F = 0
j = 1
while (j <= n-k+1):
a = scipy.special.binom(n,j)
b = F(n-j,k-1)
F = F + a*b
j = j + 1
return F
The problem with @ArielLeung's code is that it defines both the function F(n,k) and the variable returned F as F. This creates ambiguity in the variable namespace.
The following should work fine.
import scipy.special
def F(n,k):
f = 0
if (k == 1):
f = 1
else:
f = 0
j = 1
while (j <= n-k+1):
a = scipy.special.binom(n,j)
b = F(n-j,k-1)
f = f + a*b
j = j + 1
return f
However, I would prefer @Nikaidoh's list comprehension as a much concise solution.
accept the best answer. How to accept an answerYou need something like this:
import scipy.special
def F(n,k):
if (k == 1):
return 1
else:
return sum(scipy.special.binom(n,j) * F(n-j,k-1) for j in range(1, n-k+2))
In your code you are reassigning to F, which you define as function (def F(n,k)), the value of an int (F = 1). In this way, when the value k is greater than 1 you get this error:
b = F(n-j,k-1)
TypeError: 'int' object is not callable
Because now F is an int, not a function anymore
sum()? No real reason to gather the iterable into a list before summing.
