# IterableSimplexGrid¶

class poisson_approval.IterableSimplexGrid(cls, denominator, keys, d_key_fixed_share=None, test=None, **kwargs)[source]

Iterate over some objects defined by shares on a discrete simplex.

Parameters: cls (class) – The class of object we want to create. It must accept as parameter a dictionary of the form key: share, where share is a number. denominator (int or iterable) – The grain(s) of the grid. keys (iterable) – These keys will have a variable share. d_key_fixed_share (dict) – A dictionary. For each entry key: fixed_share, this key will have at least this fixed share. The total must be lower or equal to 1. test (callable) – A function cls -> bool. kwargs – Additional parameters are passed to cls when creating the object.

Examples

Basic usage:

>>> from fractions import Fraction
>>> for d in IterableSimplexGrid(cls=DictPrintingInOrder, denominator=3, keys=['a', 'b']):
...     print(d)
{a: 1, b: 0}
{a: 2/3, b: 1/3}
{a: 1/3, b: 2/3}
{a: 0, b: 1}


It is possible to specify an iterable of denominators:

>>> from fractions import Fraction
>>> for d in IterableSimplexGrid(cls=DictPrintingInOrder, denominator=range(2, 4), keys=['a', 'b']):
...     print(d)
{a: 1, b: 0}
{a: 1/2, b: 1/2}
{a: 0, b: 1}
{a: 1, b: 0}
{a: 2/3, b: 1/3}
{a: 1/3, b: 2/3}
{a: 0, b: 1}


If d_key_fixed_share is given, then these shares are fixed, and the remaining share is split between keys:

>>> for d in IterableSimplexGrid(cls=DictPrintingInOrder, denominator=3, keys=['a', 'b'],
...                              d_key_fixed_share={'c': Fraction(1, 2)}):
...     print(d)
{a: 1/2, b: 0, c: 1/2}
{a: 1/3, b: 1/6, c: 1/2}
{a: 1/6, b: 1/3, c: 1/2}
{a: 0, b: 1/2, c: 1/2}


The keys in d_fixed_share may overlap with keys:

>>> for d in IterableSimplexGrid(cls=DictPrintingInOrder, denominator=3, keys=['a', 'b'],
...                              d_key_fixed_share={'b': Fraction(1, 2)}):
...     print(d)
{a: 1/2, b: 1/2}
{a: 1/3, b: 2/3}
{a: 1/6, b: 5/6}
{a: 0, b: 1}


It is possible to add a condition with the parameter test:

>>> def test_small_euclidean_norm(d):
...     return sum(x**2 for x in d.values()) < 0.6
>>> for d in IterableSimplexGrid(cls=DictPrintingInOrder, denominator=11, keys=['a', 'b'],
...                              test=test_small_euclidean_norm):
...     print(d)
{a: 7/11, b: 4/11}
{a: 6/11, b: 5/11}
{a: 5/11, b: 6/11}
{a: 4/11, b: 7/11}