def phase_by_transmission(g, window_size, copy=True):
"""Phase genotypes in a trio or cross where possible using Mendelian
transmission.
Parameters
----------
g : array_like, int, shape (n_variants, n_samples, 2)
Genotype array, with parents as first two columns and progeny as
remaining columns.
window_size : int
Number of previous heterozygous sites to include when phasing each
parent. A number somewhere between 10 and 100 may be appropriate,
depending on levels of heterozygosity and quality of data.
copy : bool, optional
If False, attempt to phase genotypes in-place. Note that this is
only possible if the input array has int8 dtype, otherwise a copy is
always made regardless of this parameter.
Returns
-------
g : GenotypeArray
Genotype array with progeny phased where possible.
"""
# setup
g = np.asarray(g, dtype='i1')
g = GenotypeArray(g, copy=copy)
g._values = memoryview_safe(g.values)
check_ploidy(g.ploidy, 2)
check_min_samples(g.n_samples, 3)
# phase the progeny
is_phased = _opt_phase_progeny_by_transmission(g.values)
g.is_phased = np.asarray(is_phased).view(bool)
# phase the parents
_opt_phase_parents_by_transmission(g.values, is_phased, window_size)
return g
def phase_progeny_by_transmission(g):
"""Phase progeny genotypes from a trio or cross using Mendelian
transmission.
Parameters
----------
g : array_like, int, shape (n_variants, n_samples, 2)
Genotype array, with parents as first two columns and progeny as
remaining columns.
Returns
-------
g : ndarray, int8, shape (n_variants, n_samples, 2)
Genotype array with progeny phased where possible.
Examples
--------
>>> import allel
>>> g = allel.GenotypeArray([
... [[0, 0], [0, 0], [0, 0]],
... [[1, 1], [1, 1], [1, 1]],
... [[0, 0], [1, 1], [0, 1]],
... [[1, 1], [0, 0], [0, 1]],
... [[0, 0], [0, 1], [0, 0]],
... [[0, 0], [0, 1], [0, 1]],
... [[0, 1], [0, 0], [0, 1]],
... [[0, 1], [0, 1], [0, 1]],
... [[0, 1], [1, 2], [0, 1]],
... [[1, 2], [0, 1], [1, 2]],
... [[0, 1], [2, 3], [0, 2]],
... [[2, 3], [0, 1], [1, 3]],
... [[0, 0], [0, 0], [-1, -1]],
... [[0, 0], [0, 0], [1, 1]],
... ], dtype='i1')
>>> g = allel.phase_progeny_by_transmission(g)
>>> print(g.to_str(row_threshold=None))
0/0 0/0 0|0
1/1 1/1 1|1
0/0 1/1 0|1
1/1 0/0 1|0
0/0 0/1 0|0
0/0 0/1 0|1
0/1 0/0 1|0
0/1 0/1 0/1
0/1 1/2 0|1
1/2 0/1 2|1
0/1 2/3 0|2
2/3 0/1 3|1
0/0 0/0 ./.
0/0 0/0 1/1
>>> g.is_phased
array([[False, False, True],
[False, False, True],
[False, False, True],
[False, False, True],
[False, False, True],
[False, False, True],
[False, False, True],
[False, False, False],
[False, False, True],
[False, False, True],
[False, False, True],
[False, False, True],
[False, False, False],
[False, False, False]])
"""
# setup
g = GenotypeArray(g, dtype='i1', copy=True)
check_ploidy(g.ploidy, 2)
check_min_samples(g.n_samples, 3)
# run the phasing
# N.B., a copy has already been made, so no need to make memoryview safe
is_phased = _opt_phase_progeny_by_transmission(g.values)
g.is_phased = np.asarray(is_phased).view(bool)
# outputs
return g
