prd module

Idiomatic implementation of a Python function that calculates the product of the items from an iterable.

prd.prd.prd(iterable: Iterable, start: Optional[Any] = 1) → Any

Idiomatic implementation of a product function (an analog of – and complement to – the built-in sum function). This function applies the built-in multiplication operator operator.mul to all of the items from the supplied iterable.

>>> prd([1, 2, 3, 4])
24
>>> prd([2])
2
>>> prd([1.2, 3.4, 5.6])
22.848
>>> prd([])
1

The function is compatible with objects for which the built-in multiplication operator is defined.

>>> class var(str):
...     def __mul__(self, other):
...         return self + ' * ' + other
...     def __rmul__(self, other):
...         return other + ' * ' + self
>>> prd([var('b'), var('c'), var('d')], var('a'))
'a * b * c * d'

The start parameter and the elements found in the iterable can be of different types. It is only required that the output of the multiplication operation can by multiplied with the next element from the iterable.

>>> prd([], 'a')
'a'
>>> prd([1, 2, 3], 'a')
'aaaaaa'
>>> prd(['a', 3], 2)
'aaaaaa'

If a supplied argument is missing or unsupported, a descriptive exceptions is raised.

>>> prd()
Traceback (most recent call last):
  ...
TypeError: prd() missing 1 required positional argument: 'iterable'
>>> prd(123)
Traceback (most recent call last):
  ...
TypeError: argument must support iteration
>>> prd('abc')
Traceback (most recent call last):
  ...
TypeError: can't multiply sequence by non-int of type 'str'
>>> prd([None])
Traceback (most recent call last):
    ...
TypeError: unsupported operand type(s) for *: 'int' and 'NoneType'