comnum.Ccdm#

class comnum.Ccdm(composition)#

Constant-composition distribution matching (Schulte & Böcherer 2016): k uniform bits to a sequence of n symbols of a fixed composition, by enumerative coding.

Parameters:: composition (list[int]) – occurrences of every symbol in a block.
Raises:: ValueError – for an invalid parameter (the message names it).

Examples

>>> import comnum, numpy as np
>>> m = comnum.Ccdm([2, 1, 1])
>>> b = np.zeros(m.k, dtype=np.uint8)
>>> m.dematch(m.match_bits(b)).tolist() == b.tolist()
True

static from_distribution(p, n)#

The matcher of blocks of n symbols nearest to a distribution.

Parameters:

p (array_like) – the target distribution of the symbols.
n (int) – symbols per block.

Returns:

the matcher.

Return type:

Ccdm

Raises:

ValueError – for an invalid parameter or input (the message names it).

dematch(symbols)#

The bits of a block of symbols (a used-up symbol is replaced by the nearest available one).

Parameters:: symbols (array_like) – n symbol indices.
Returns:: k bits (uint8).
Return type:: numpy.ndarray
Raises:: ValueError – for an invalid parameter or input (the message names it).

match_bits(bits)#

The symbols of one block of bits.

Parameters:: bits (array_like) – k bits.
Returns:: n symbol indices (int64).
Return type:: numpy.ndarray
Raises:: ValueError – for an invalid parameter or input (the message names it).