def rogers_huff_r_between(gna, gnb, fill=np.nan):
"""Estimate the linkage disequilibrium parameter *r* for each pair of
variants between the two input arrays, using the method of Rogers and
Huff (2008).
Parameters
----------
gna, gnb : array_like, int8, shape (n_variants, n_samples)
Diploid genotypes at biallelic variants, coded as the number of
alternate alleles per call (i.e., 0 = hom ref, 1 = het, 2 = hom alt).
fill : float, optional
Value to use where r cannot be calculated.
Returns
-------
r : ndarray, float, shape (m_variants, n_variants )
Matrix in rectangular form.
"""
# check inputs
gna = asarray_ndim(gna, 2, dtype='i1')
gnb = asarray_ndim(gnb, 2, dtype='i1')
gna = memoryview_safe(gna)
gnb = memoryview_safe(gnb)
# compute correlation coefficients
r = gn_pairwise2_corrcoef_int8(gna, gnb, fill)
# convenience for singletons
if r.size == 1:
r = r[0, 0]
return r
def voight_painting(h):
"""Paint haplotypes, assigning a unique integer to each shared haplotype
prefix.
Parameters
----------
h : array_like, int, shape (n_variants, n_haplotypes)
Haplotype array.
Returns
-------
painting : ndarray, int, shape (n_variants, n_haplotypes)
Painting array.
indices : ndarray, int, shape (n_hapotypes,)
Haplotype indices after sorting by prefix.
"""
# check inputs
# N.B., ensure int8 so we can use cython optimisation
h = HaplotypeArray(np.asarray(h), copy=False)
if h.max() > 1:
raise NotImplementedError('only biallelic variants are supported')
if h.min() < 0:
raise NotImplementedError('missing calls are not supported')
# sort by prefix
indices = h.prefix_argsort()
h = np.take(h, indices, axis=1)
# paint
painting = paint_shared_prefixes(memoryview_safe(np.asarray(h)))
return painting, indices
def rogers_huff_r(gn, fill=np.nan):
"""Estimate the linkage disequilibrium parameter *r* for each pair of
variants using the method of Rogers and Huff (2008).
Parameters
----------
gn : array_like, int8, shape (n_variants, n_samples)
Diploid genotypes at biallelic variants, coded as the number of
alternate alleles per call (i.e., 0 = hom ref, 1 = het, 2 = hom alt).
fill : float, optional
Value to use where r cannot be calculated.
Returns
-------
r : ndarray, float, shape (n_variants * (n_variants - 1) // 2,)
Matrix in condensed form.
Examples
--------
>>> import allel
>>> g = allel.GenotypeArray([[[0, 0], [1, 1], [0, 0]],
... [[0, 0], [1, 1], [0, 0]],
... [[1, 1], [0, 0], [1, 1]],
... [[0, 0], [0, 1], [-1, -1]]], dtype='i1')
>>> gn = g.to_n_alt(fill=-1)
>>> gn
array([[ 0, 2, 0],
[ 0, 2, 0],
[ 2, 0, 2],
[ 0, 1, -1]], dtype=int8)
>>> r = allel.stats.rogers_huff_r(gn)
>>> r # doctest: +ELLIPSIS
array([ 1. , -1.00000012, 1. , -1.00000012, 1. , -1. ], ...
>>> r ** 2 # doctest: +ELLIPSIS
array([ 1. , 1.00000024, 1. , 1.00000024, 1. , 1. ], ...
>>> from scipy.spatial.distance import squareform
>>> squareform(r ** 2)
array([[ 0. , 1. , 1.00000024, 1. ],
[ 1. , 0. , 1.00000024, 1. ],
[ 1.00000024, 1.00000024, 0. , 1. ],
[ 1. , 1. , 1. , 0. ]], dtype=float32)
"""
# check inputs
gn = asarray_ndim(gn, 2, dtype='i1')
gn = memoryview_safe(gn)
# compute correlation coefficients
r = gn_pairwise_corrcoef_int8(gn, fill)
# convenience for singletons
if r.size == 1:
r = r[0]
return r
def locate_unlinked(gn, size=100, step=20, threshold=.1, blen=None):
"""Locate variants in approximate linkage equilibrium, where r**2 is
below the given `threshold`.
Parameters
----------
gn : array_like, int8, shape (n_variants, n_samples)
Diploid genotypes at biallelic variants, coded as the number of
alternate alleles per call (i.e., 0 = hom ref, 1 = het, 2 = hom alt).
size : int
Window size (number of variants).
step : int
Number of variants to advance to the next window.
threshold : float
Maximum value of r**2 to include variants.
blen : int, optional
Block length to use for chunked computation.
Returns
-------
loc : ndarray, bool, shape (n_variants)
Boolean array where True items locate variants in approximate
linkage equilibrium.
Notes
-----
The value of r**2 between each pair of variants is calculated using the
method of Rogers and Huff (2008).
"""
# check inputs
if not hasattr(gn, 'shape') or not hasattr(gn, 'dtype'):
gn = np.asarray(gn, dtype='i1')
if gn.ndim != 2:
raise ValueError('gn must have two dimensions')
# setup output
loc = np.ones(gn.shape[0], dtype='u1')
# compute in chunks to avoid loading big arrays into memory
blen = get_blen_array(gn, blen)
blen = max(blen, 10 * size) # avoid too small chunks
n_variants = gn.shape[0]
for i in range(0, n_variants, blen):
# N.B., ensure overlap with next window
j = min(n_variants, i + blen + size)
gnb = np.asarray(gn[i:j], dtype='i1')
gnb = memoryview_safe(gnb)
locb = loc[i:j]
gn_locate_unlinked_int8(gnb, locb, size, step, threshold)
return loc.astype('b1')
def phase_parents_by_transmission(g, window_size):
"""Phase parent genotypes from a trio or cross, given progeny genotypes
already phased by Mendelian transmission.
Parameters
----------
g : GenotypeArray
Genotype array, with parents as first two columns and progeny as
remaining columns, where progeny genotypes are already phased.
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.
Returns
-------
g : GenotypeArray
Genotype array with parents phased where possible.
"""
# setup
check_type(g, GenotypeArray)
check_dtype(g.values, 'i1')
check_ploidy(g.ploidy, 2)
if g.is_phased is None:
raise ValueError(
'genotype array must first have progeny phased by transmission')
check_min_samples(g.n_samples, 3)
# run the phasing
g._values = memoryview_safe(g.values)
g._is_phased = memoryview_safe(g.is_phased)
_opt_phase_parents_by_transmission(g.values, g.is_phased.view('u1'),
window_size)
# outputs
return g
def ehh_decay(h, truncate=False):
"""Compute the decay of extended haplotype homozygosity (EHH)
moving away from the first variant.
Parameters
----------
h : array_like, int, shape (n_variants, n_haplotypes)
Haplotype array.
truncate : bool, optional
If True, the return array will exclude trailing zeros.
Returns
-------
ehh : ndarray, float, shape (n_variants, )
EHH at successive variants from the first variant.
"""
# check inputs
# N.B., ensure int8 so we can use cython optimisation
h = HaplotypeArray(np.asarray(h), copy=False)
if h.max() > 1:
raise NotImplementedError('only biallelic variants are supported')
if h.min() < 0:
raise NotImplementedError('missing calls are not supported')
# initialise
n_variants = h.n_variants # number of rows, i.e., variants
n_haplotypes = h.n_haplotypes # number of columns, i.e., haplotypes
n_pairs = (n_haplotypes * (n_haplotypes - 1)) // 2
# compute the shared prefix length between all pairs of haplotypes
spl = pairwise_shared_prefix_lengths(memoryview_safe(np.asarray(h)))
# compute EHH by counting the number of shared prefixes extending beyond
# each variant
minlength = None if truncate else n_variants + 1
b = np.bincount(spl, minlength=minlength)
c = np.cumsum(b[::-1])[:-1]
ehh = (c / n_pairs)[::-1]
return ehh
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 tabulate_state_blocks(x, states, pos=None):
"""Construct a dataframe where each row provides information about continuous state blocks.
Parameters
----------
x : array_like, int
1-dimensional array of state values.
states : set
Set of states of interest. Any state value not in this set will be ignored.
pos : array_like, int, optional
Array of positions corresponding to values in `x`.
Returns
-------
df : DataFrame
Examples
--------
>>> import allel
>>> x = [1, 1, 0, 1, 1, 2, 2, 0, 2, 1, 1]
>>> df = allel.tabulate_state_blocks(x, states={1, 2})
>>> df
state support start_lidx ... size_min size_max is_marginal
0 1 4 -1 ... 5 -1 True
1 2 3 4 ... 4 4 False
2 1 2 8 ... 2 -1 True
[3 rows x 9 columns]
>>> pos = [2, 4, 7, 8, 10, 14, 19, 23, 28, 30, 31]
>>> df = allel.tabulate_state_blocks(x, states={1, 2}, pos=pos)
>>> df
state support start_lidx ... stop_rpos length_min length_max
0 1 4 -1 ... 14 9 -1
1 2 3 4 ... 30 15 19
2 1 2 8 ... -1 2 -1
[3 rows x 15 columns]
"""
# check inputs
x = asarray_ndim(x, 1)
check_integer_dtype(x)
x = memoryview_safe(x)
# find state transitions
switch_points, transitions, observations = state_transitions(x, states)
# setup some helpers
t = transitions[1:, 0]
o = observations[1:]
s1 = switch_points[:-1]
s2 = switch_points[1:]
is_marginal = (s1[:, 0] < 0) | (s2[:, 1] < 0)
size_min = s2[:, 0] - s1[:, 1] + 1
size_max = s2[:, 1] - s1[:, 0] - 1
size_max[is_marginal] = -1
# start to build a dataframe
items = [
('state', t),
('support', o),
('start_lidx', s1[:, 0]),
('start_ridx', s1[:, 1]),
('stop_lidx', s2[:, 0]),
('stop_ridx', s2[:, 1]),
('size_min', size_min),
('size_max', size_max),
('is_marginal', is_marginal)
]
# deal with optional positions
if pos is not None:
pos = asarray_ndim(pos, 1)
check_dim0_aligned(x, pos)
check_integer_dtype(pos)
# obtain switch positions
switch_positions = np.take(pos, switch_points)
# deal with boundary transitions
switch_positions[0, 0] = -1
switch_positions[-1, 1] = -1
# setup helpers
p1 = switch_positions[:-1]
p2 = switch_positions[1:]
length_min = p2[:, 0] - p1[:, 1] + 1
length_max = p2[:, 1] - p1[:, 0] - 1
length_max[is_marginal] = -1
items += [
('start_lpos', p1[:, 0]),
('start_rpos', p1[:, 1]),
('stop_lpos', p2[:, 0]),
('stop_rpos', p2[:, 1]),
('length_min', length_min),
('length_max', length_max),
]
import pandas
return pandas.DataFrame.from_dict(OrderedDict(items))
def tabulate_state_transitions(x, states, pos=None):
"""Construct a dataframe where each row provides information about a state transition.
Parameters
----------
x : array_like, int
1-dimensional array of state values.
states : set
Set of states of interest. Any state value not in this set will be ignored.
pos : array_like, int, optional
Array of positions corresponding to values in `x`.
Returns
-------
df : DataFrame
Notes
-----
The resulting dataframe includes one row at the start representing the first state
observation and one row at the end representing the last state observation.
Examples
--------
>>> import allel
>>> x = [1, 1, 0, 1, 1, 2, 2, 0, 2, 1, 1]
>>> df = allel.tabulate_state_transitions(x, states={1, 2})
>>> df
lstate rstate lidx ridx
0 -1 1 -1 0
1 1 2 4 5
2 2 1 8 9
3 1 -1 10 -1
>>> pos = [2, 4, 7, 8, 10, 14, 19, 23, 28, 30, 31]
>>> df = allel.tabulate_state_transitions(x, states={1, 2}, pos=pos)
>>> df
lstate rstate lidx ridx lpos rpos
0 -1 1 -1 0 -1 2
1 1 2 4 5 10 14
2 2 1 8 9 28 30
3 1 -1 10 -1 31 -1
"""
# check inputs
x = asarray_ndim(x, 1)
check_integer_dtype(x)
x = memoryview_safe(x)
# find state transitions
switch_points, transitions, _ = state_transitions(x, states)
# start to build a dataframe
items = [('lstate', transitions[:, 0]),
('rstate', transitions[:, 1]),
('lidx', switch_points[:, 0]),
('ridx', switch_points[:, 1])]
# deal with optional positions
if pos is not None:
pos = asarray_ndim(pos, 1)
check_dim0_aligned(x, pos)
check_integer_dtype(pos)
# find switch positions
switch_positions = np.take(pos, switch_points)
# deal with boundary transitions
switch_positions[0, 0] = -1
switch_positions[-1, 1] = -1
# add columns into dataframe
items += [('lpos', switch_positions[:, 0]),
('rpos', switch_positions[:, 1])]
import pandas
return pandas.DataFrame.from_dict(OrderedDict(items))
def xpnsl(h1, h2, use_threads=True):
"""Cross-population version of the NSL statistic.
Parameters
----------
h1 : array_like, int, shape (n_variants, n_haplotypes)
Haplotype array for the first population.
h2 : array_like, int, shape (n_variants, n_haplotypes)
Haplotype array for the second population.
use_threads : bool, optional
If True use multiple threads to compute.
Returns
-------
score : ndarray, float, shape (n_variants,)
Unstandardized XPNSL scores.
"""
# check inputs
h1 = asarray_ndim(h1, 2)
check_integer_dtype(h1)
h2 = asarray_ndim(h2, 2)
check_integer_dtype(h2)
check_dim0_aligned(h1, h2)
h1 = memoryview_safe(h1)
h2 = memoryview_safe(h2)
if use_threads and multiprocessing.cpu_count() > 1:
# use multiple threads
# setup threadpool
pool = ThreadPool(min(4, multiprocessing.cpu_count()))
# scan forward
res1_fwd = pool.apply_async(nsl_scan, args=(h1, ))
res2_fwd = pool.apply_async(nsl_scan, args=(h2, ))
# scan backward
res1_rev = pool.apply_async(nsl_scan, args=(h1[::-1], ))
res2_rev = pool.apply_async(nsl_scan, args=(h2[::-1], ))
# wait for both to finish
pool.close()
pool.join()
# obtain results
nsl1_fwd = res1_fwd.get()
nsl2_fwd = res2_fwd.get()
nsl1_rev = res1_rev.get()
nsl2_rev = res2_rev.get()
# cleanup
pool.terminate()
else:
# compute without threads
# scan forward
nsl1_fwd = nsl_scan(h1)
nsl2_fwd = nsl_scan(h2)
# scan backward
nsl1_rev = nsl_scan(h1[::-1])
nsl2_rev = nsl_scan(h2[::-1])
# handle reverse scans
nsl1_rev = nsl1_rev[::-1]
nsl2_rev = nsl2_rev[::-1]
# compute unstandardized score
nsl1 = nsl1_fwd + nsl1_rev
nsl2 = nsl2_fwd + nsl2_rev
score = np.log(nsl1 / nsl2)
return score
def nsl(h, use_threads=True):
"""Compute the unstandardized number of segregating sites by length (nSl)
for each variant, comparing the reference and alternate alleles,
after Ferrer-Admetlla et al. (2014).
Parameters
----------
h : array_like, int, shape (n_variants, n_haplotypes)
Haplotype array.
use_threads : bool, optional
If True use multiple threads to compute.
Returns
-------
score : ndarray, float, shape (n_variants,)
Notes
-----
This function will calculate nSl for all variants. To exclude variants
below a given minor allele frequency, filter the input haplotype array
before passing to this function.
This function computes nSl by comparing the reference and alternate
alleles. These can be polarised by switching the sign for any variant where
the reference allele is derived.
This function does nothing about nSl calculations where haplotype
homozygosity extends up to the first or last variant. There may be edge
effects.
Note that the unstandardized score is returned. Usually these scores are
then standardized in different allele frequency bins.
See Also
--------
standardize_by_allele_count
"""
# check inputs
h = asarray_ndim(h, 2)
check_integer_dtype(h)
h = memoryview_safe(h)
# # check there are no invariant sites
# ac = h.count_alleles()
# assert np.all(ac.is_segregating()), 'please remove non-segregating sites'
if use_threads and multiprocessing.cpu_count() > 1:
# create pool
pool = ThreadPool(2)
# scan forward
result_fwd = pool.apply_async(nsl01_scan, args=(h, ))
# scan backward
result_rev = pool.apply_async(nsl01_scan, args=(h[::-1], ))
# wait for both to finish
pool.close()
pool.join()
# obtain results
nsl0_fwd, nsl1_fwd = result_fwd.get()
nsl0_rev, nsl1_rev = result_rev.get()
else:
# scan forward
nsl0_fwd, nsl1_fwd = nsl01_scan(h)
# scan backward
nsl0_rev, nsl1_rev = nsl01_scan(h[::-1])
# handle backwards
nsl0_rev = nsl0_rev[::-1]
nsl1_rev = nsl1_rev[::-1]
# compute unstandardized score
nsl0 = nsl0_fwd + nsl0_rev
nsl1 = nsl1_fwd + nsl1_rev
score = np.log(nsl1 / nsl0)
return score
def xpehh(h1,
h2,
pos,
map_pos=None,
min_ehh=0.05,
include_edges=False,
gap_scale=20000,
max_gap=200000,
is_accessible=None,
use_threads=True):
"""Compute the unstandardized cross-population extended haplotype
homozygosity score (XPEHH) for each variant.
Parameters
----------
h1 : array_like, int, shape (n_variants, n_haplotypes)
Haplotype array for the first population.
h2 : array_like, int, shape (n_variants, n_haplotypes)
Haplotype array for the second population.
pos : array_like, int, shape (n_variants,)
Variant positions on physical or genetic map.
map_pos : array_like, float, shape (n_variants,)
Variant positions (genetic map distance).
min_ehh: float, optional
Minimum EHH beyond which to truncate integrated haplotype
homozygosity calculation.
include_edges : bool, optional
If True, report scores even if EHH does not decay below `min_ehh`
before reaching the edge of the data.
gap_scale : int, optional
Rescale distance between variants if gap is larger than this value.
max_gap : int, optional
Do not report scores if EHH spans a gap larger than this number of
base pairs.
is_accessible : array_like, bool, optional
Genome accessibility array. If provided, distance between variants
will be computed as the number of accessible bases between them.
use_threads : bool, optional
If True use multiple threads to compute.
Returns
-------
score : ndarray, float, shape (n_variants,)
Unstandardized XPEHH scores.
Notes
-----
This function will calculate XPEHH for all variants. To exclude variants
below a given minor allele frequency, filter the input haplotype arrays
before passing to this function.
This function returns NaN for any EHH calculations where haplotype
homozygosity does not decay below `min_ehh` before reaching the first or
last variant. To disable this behaviour, set `include_edges` to True.
Note that the unstandardized score is returned. Usually these scores are
then standardized genome-wide.
Haplotype arrays from the two populations may have different numbers of
haplotypes.
See Also
--------
standardize
"""
# check inputs
h1 = asarray_ndim(h1, 2)
check_integer_dtype(h1)
h2 = asarray_ndim(h2, 2)
check_integer_dtype(h2)
pos = asarray_ndim(pos, 1)
check_dim0_aligned(h1, h2, pos)
h1 = memoryview_safe(h1)
h2 = memoryview_safe(h2)
pos = memoryview_safe(pos)
# compute gaps between variants for integration
gaps = compute_ihh_gaps(pos, map_pos, gap_scale, max_gap, is_accessible)
# setup kwargs
kwargs = dict(min_ehh=min_ehh, include_edges=include_edges)
if use_threads and multiprocessing.cpu_count() > 1:
# use multiple threads
# setup threadpool
pool = ThreadPool(min(4, multiprocessing.cpu_count()))
# scan forward
res1_fwd = pool.apply_async(ihh_scan, (h1, gaps), kwargs)
res2_fwd = pool.apply_async(ihh_scan, (h2, gaps), kwargs)
# scan backward
res1_rev = pool.apply_async(ihh_scan, (h1[::-1], gaps[::-1]), kwargs)
res2_rev = pool.apply_async(ihh_scan, (h2[::-1], gaps[::-1]), kwargs)
# wait for both to finish
pool.close()
pool.join()
# obtain results
ihh1_fwd = res1_fwd.get()
ihh2_fwd = res2_fwd.get()
ihh1_rev = res1_rev.get()
ihh2_rev = res2_rev.get()
# cleanup
pool.terminate()
else:
# compute without threads
# scan forward
ihh1_fwd = ihh_scan(h1, gaps, **kwargs)
ihh2_fwd = ihh_scan(h2, gaps, **kwargs)
# scan backward
ihh1_rev = ihh_scan(h1[::-1], gaps[::-1], **kwargs)
ihh2_rev = ihh_scan(h2[::-1], gaps[::-1], **kwargs)
# handle reverse scans
ihh1_rev = ihh1_rev[::-1]
ihh2_rev = ihh2_rev[::-1]
# compute unstandardized score
ihh1 = ihh1_fwd + ihh1_rev
ihh2 = ihh2_fwd + ihh2_rev
score = np.log(ihh1 / ihh2)
return score
def ihs(h,
pos,
map_pos=None,
min_ehh=0.05,
min_maf=0.05,
include_edges=False,
gap_scale=20000,
max_gap=200000,
is_accessible=None,
use_threads=True):
"""Compute the unstandardized integrated haplotype score (IHS) for each
variant, comparing integrated haplotype homozygosity between the
reference (0) and alternate (1) alleles.
Parameters
----------
h : array_like, int, shape (n_variants, n_haplotypes)
Haplotype array.
pos : array_like, int, shape (n_variants,)
Variant positions (physical distance).
map_pos : array_like, float, shape (n_variants,)
Variant positions (genetic map distance).
min_ehh: float, optional
Minimum EHH beyond which to truncate integrated haplotype
homozygosity calculation.
min_maf : float, optional
Do not compute integrated haplotype homozogysity for variants with
minor allele frequency below this value.
include_edges : bool, optional
If True, report scores even if EHH does not decay below `min_ehh`
before reaching the edge of the data.
gap_scale : int, optional
Rescale distance between variants if gap is larger than this value.
max_gap : int, optional
Do not report scores if EHH spans a gap larger than this number of
base pairs.
is_accessible : array_like, bool, optional
Genome accessibility array. If provided, distance between variants
will be computed as the number of accessible bases between them.
use_threads : bool, optional
If True use multiple threads to compute.
Returns
-------
score : ndarray, float, shape (n_variants,)
Unstandardized IHS scores.
Notes
-----
This function will calculate IHS for all variants. To exclude variants
below a given minor allele frequency, filter the input haplotype array
before passing to this function.
This function computes IHS comparing the reference and alternate alleles.
These can be polarised by switching the sign for any variant where the
reference allele is derived.
This function returns NaN for any IHS calculations where haplotype
homozygosity does not decay below `min_ehh` before reaching the first or
last variant. To disable this behaviour, set `include_edges` to True.
Note that the unstandardized score is returned. Usually these scores are
then standardized in different allele frequency bins.
See Also
--------
standardize_by_allele_count
"""
# check inputs
h = asarray_ndim(h, 2)
check_integer_dtype(h)
pos = asarray_ndim(pos, 1)
check_dim0_aligned(h, pos)
h = memoryview_safe(h)
pos = memoryview_safe(pos)
# compute gaps between variants for integration
gaps = compute_ihh_gaps(pos, map_pos, gap_scale, max_gap, is_accessible)
# setup kwargs
kwargs = dict(min_ehh=min_ehh,
min_maf=min_maf,
include_edges=include_edges)
if use_threads and multiprocessing.cpu_count() > 1:
# run with threads
# create pool
pool = ThreadPool(2)
# scan forward
result_fwd = pool.apply_async(ihh01_scan, (h, gaps), kwargs)
# scan backward
result_rev = pool.apply_async(ihh01_scan, (h[::-1], gaps[::-1]),
kwargs)
# wait for both to finish
pool.close()
pool.join()
# obtain results
ihh0_fwd, ihh1_fwd = result_fwd.get()
ihh0_rev, ihh1_rev = result_rev.get()
# cleanup
pool.terminate()
else:
# run without threads
# scan forward
ihh0_fwd, ihh1_fwd = ihh01_scan(h, gaps, **kwargs)
# scan backward
ihh0_rev, ihh1_rev = ihh01_scan(h[::-1], gaps[::-1], **kwargs)
# handle reverse scan
ihh0_rev = ihh0_rev[::-1]
ihh1_rev = ihh1_rev[::-1]
# compute unstandardized score
ihh0 = ihh0_fwd + ihh0_rev
ihh1 = ihh1_fwd + ihh1_rev
score = np.log(ihh1 / ihh0)
return score
