## Question

Asked By – Morlock

I need to compute combinatorials (nCr) in Python but cannot find the function to do that in `math`

, `numpy`

or `stat`

libraries. Something like a function of the type:

```
comb = calculate_combinations(n, r)
```

I need the number of possible combinations, not the actual combinations, so `itertools.combinations`

does not interest me.

Finally, I want to avoid using factorials, as the numbers I’ll be calculating the combinations for can get too big and the factorials are going to be monstrous.

This seems like a REALLY easy to answer question, however I am being drowned in questions about generating all the actual combinations, which is not what I want.

**Now we will see solution for issue: Statistics: combinations in Python **

## Answer

See scipy.special.comb (scipy.misc.comb in older versions of scipy). When `exact`

is False, it uses the gammaln function to obtain good precision without taking much time. In the exact case it returns an arbitrary-precision integer, which might take a long time to compute.

This question is answered By – Jouni K. Seppänen