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Add tests to check LS HMM of tskit compared to BEAGLE
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szhan committed Aug 8, 2023
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251 changes: 251 additions & 0 deletions python/tests/test_imputation.py
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"""
Tests for genotype imputation (forward and Baum-Welsh algorithms).
"""
import io

import numpy as np

import tskit


# A tree sequence containing 3 diploid individuals with 5 sites and 5 mutations
# (one per site). The first 2 individuals are used as reference panel,
# the last one is the target individual.

_toy_ts_nodes_text = """\
id is_sample time population individual metadata
0 1 0.000000 0 0
1 1 0.000000 0 0
2 1 0.000000 0 1
3 1 0.000000 0 1
4 1 0.000000 0 2
5 1 0.000000 0 2
6 0 0.029768 0 -1
7 0 0.133017 0 -1
8 0 0.223233 0 -1
9 0 0.651586 0 -1
10 0 0.698831 0 -1
11 0 2.114867 0 -1
12 0 4.322031 0 -1
13 0 7.432311 0 -1
"""

_toy_ts_edges_text = """\
left right parent child metadata
0.000000 1000000.000000 6 0
0.000000 1000000.000000 6 3
0.000000 1000000.000000 7 2
0.000000 1000000.000000 7 5
0.000000 1000000.000000 8 1
0.000000 1000000.000000 8 4
0.000000 781157.000000 9 6
0.000000 781157.000000 9 7
0.000000 505438.000000 10 8
0.000000 505438.000000 10 9
505438.000000 549484.000000 11 8
505438.000000 549484.000000 11 9
781157.000000 1000000.000000 12 6
781157.000000 1000000.000000 12 7
549484.000000 1000000.000000 13 8
549484.000000 781157.000000 13 9
781157.000000 1000000.000000 13 12
"""

_toy_ts_sites_text = """\
position ancestral_state metadata
200000.000000 A
300000.000000 C
520000.000000 G
600000.000000 T
900000.000000 A
"""

_toy_ts_mutations_text = """\
site node time derived_state parent metadata
0 9 unknown G -1
1 8 unknown A -1
2 9 unknown T -1
3 9 unknown C -1
4 12 unknown C -1
"""

_toy_ts_individuals_text = """\
flags
0
0
0
"""


def get_toy_ts():
"""
Returns the toy tree sequence in text format above.
"""
ts = tskit.load_text(
nodes=io.StringIO(_toy_ts_nodes_text),
edges=io.StringIO(_toy_ts_edges_text),
sites=io.StringIO(_toy_ts_sites_text),
mutations=io.StringIO(_toy_ts_mutations_text),
individuals=io.StringIO(_toy_ts_individuals_text),
strict=False,
)
return ts


# BEAGLE 4.1 was run on the toy data set above using default parameters.
# The following are the forward probability matrices and backward probability
# matrices calculated when imputing into the third individual above. There are
# two sets of matrices, one for each haplotype.
#
# Notes about calculations:
# n = number of haplotypes in ref. panel
# M = number of markers
# m = index of marker (site)
# h = index of haplotype in ref. panel
#
# In forward probability matrix,
# fwd[m][h] = emission prob., if m = 0 (first marker)
# fwd[m][h] = emission prob. * (scale * fwd[m - 1][h] + shift), otherwise
# where scale = (1 - switch prob.)/sum of fwd[m - 1],
# and shift = switch prob./n.
#
# In backward probability matrix,
# bwd[m][h] = 1, if m = M - 1 (last marker) // DON'T SEE THIS IN BEAGLE
# unadj. bwd[m][h] = emission prob. / n
# bwd[m][h] = (unadj. bwd[m][h] + shift) * scale, otherwise
# where scale = (1 - switch prob.)/sum of unadj. bwd[m],
# and shift = switch prob./n.
#
# For each site, the sum of backward value over all haplotypes is calculated
# before scaling and shifting.

_fwd_matrix_text_1 = """
m,h,probRec,probNoRec,noErrProb,errProb,refAl,queryAl,shift,scale,sum,val
0,0,0.000000,1.000000,0.999900,0.000100,1,0,0.000000,1.000000,0.000100,0.000100
0,1,0.000000,1.000000,0.999900,0.000100,0,0,0.000000,1.000000,1.000000,0.999900
0,2,0.000000,1.000000,0.999900,0.000100,1,0,0.000000,1.000000,1.000100,0.000100
0,3,0.000000,1.000000,0.999900,0.000100,1,0,0.000000,1.000000,1.000200,0.000100
1,0,1.000000,0.000000,0.999900,0.000100,0,1,0.250000,0.000000,0.000025,0.000025
1,1,1.000000,0.000000,0.999900,0.000100,1,1,0.250000,0.000000,0.250000,0.249975
1,2,1.000000,0.000000,0.999900,0.000100,0,1,0.250000,0.000000,0.250025,0.000025
1,3,1.000000,0.000000,0.999900,0.000100,0,1,0.250000,0.000000,0.250050,0.000025
2,0,1.000000,0.000000,0.999900,0.000100,1,0,0.250000,0.000000,0.000025,0.000025
2,1,1.000000,0.000000,0.999900,0.000100,0,0,0.250000,0.000000,0.250000,0.249975
2,2,1.000000,0.000000,0.999900,0.000100,1,0,0.250000,0.000000,0.250025,0.000025
2,3,1.000000,0.000000,0.999900,0.000100,1,0,0.250000,0.000000,0.250050,0.000025
3,0,1.000000,0.000000,0.999900,0.000100,1,0,0.250000,0.000000,0.000025,0.000025
3,1,1.000000,0.000000,0.999900,0.000100,0,0,0.250000,0.000000,0.250000,0.249975
3,2,1.000000,0.000000,0.999900,0.000100,1,0,0.250000,0.000000,0.250025,0.000025
3,3,1.000000,0.000000,0.999900,0.000100,1,0,0.250000,0.000000,0.250050,0.000025
"""

_bwd_matrix_text_1 = """
m,h,probRec,probNoRec,noErrProb,errProb,refAl,queryAl,shift,scale,sum,val
3,0,-1,-1,-1,-1,-1,-1,-1,-1,-1,1.000000
3,1,-1,-1,-1,-1,-1,-1,-1,-1,-1,1.000000
3,2,-1,-1,-1,-1,-1,-1,-1,-1,-1,1.000000
3,3,-1,-1,-1,-1,-1,-1,-1,-1,-1,1.000000
2,0,1.000000,0.000000,0.999900,0.000100,1,0,0.000000,0.250000,0.250050,0.250000
2,1,1.000000,0.000000,0.999900,0.000100,0,0,0.000000,0.250000,0.250050,0.250000
2,2,1.000000,0.000000,0.999900,0.000100,1,0,0.000000,0.250000,0.250050,0.250000
2,3,1.000000,0.000000,0.999900,0.000100,1,0,0.000000,0.250000,0.250050,0.250000
1,0,1.000000,0.000000,0.999900,0.000100,0,0,0.000000,0.250000,0.250050,0.250000
1,1,1.000000,0.000000,0.999900,0.000100,1,0,0.000000,0.250000,0.250050,0.250000
1,2,1.000000,0.000000,0.999900,0.000100,0,0,0.000000,0.250000,0.250050,0.250000
1,3,1.000000,0.000000,0.999900,0.000100,0,0,0.000000,0.250000,0.250050,0.250000
0,0,1.000000,0.000000,0.999900,0.000100,1,1,0.000000,0.250000,0.250050,0.250000
0,1,1.000000,0.000000,0.999900,0.000100,0,1,0.000000,0.250000,0.250050,0.250000
0,2,1.000000,0.000000,0.999900,0.000100,1,1,0.000000,0.250000,0.250050,0.250000
0,3,1.000000,0.000000,0.999900,0.000100,1,1,0.000000,0.250000,0.250050,0.250000
"""

_fwd_matrix_text_2 = """
m,h,probRec,probNoRec,noErrProb,errProb,refAl,queryAl,shift,scale,sum,val
0,0,0.000000,1.000000,0.999900,0.000100,1,1,0.000000,1.000000,0.999900,0.999900
0,1,0.000000,1.000000,0.999900,0.000100,0,1,0.000000,1.000000,1.000000,0.000100
0,2,0.000000,1.000000,0.999900,0.000100,1,1,0.000000,1.000000,1.999900,0.999900
0,3,0.000000,1.000000,0.999900,0.000100,1,1,0.000000,1.000000,2.999800,0.999900
1,0,1.000000,0.000000,0.999900,0.000100,0,0,0.250000,0.000000,0.249975,0.249975
1,1,1.000000,0.000000,0.999900,0.000100,1,0,0.250000,0.000000,0.250000,0.000025
1,2,1.000000,0.000000,0.999900,0.000100,0,0,0.250000,0.000000,0.499975,0.249975
1,3,1.000000,0.000000,0.999900,0.000100,0,0,0.250000,0.000000,0.749950,0.249975
2,0,1.000000,0.000000,0.999900,0.000100,1,1,0.250000,0.000000,0.249975,0.249975
2,1,1.000000,0.000000,0.999900,0.000100,0,1,0.250000,0.000000,0.250000,0.000025
2,2,1.000000,0.000000,0.999900,0.000100,1,1,0.250000,0.000000,0.499975,0.249975
2,3,1.000000,0.000000,0.999900,0.000100,1,1,0.250000,0.000000,0.749950,0.249975
3,0,1.000000,0.000000,0.999900,0.000100,1,1,0.250000,0.000000,0.249975,0.249975
3,1,1.000000,0.000000,0.999900,0.000100,0,1,0.250000,0.000000,0.250000,0.000025
3,2,1.000000,0.000000,0.999900,0.000100,1,1,0.250000,0.000000,0.499975,0.249975
3,3,1.000000,0.000000,0.999900,0.000100,1,1,0.250000,0.000000,0.749950,0.249975
"""

_bwd_matrix_text_2 = """
m,h,probRec,probNoRec,noErrProb,errProb,refAl,queryAl,shift,scale,sum,val
3,0,-1,-1,-1,-1,-1,-1,-1,-1,-1,1.000000
3,1,-1,-1,-1,-1,-1,-1,-1,-1,-1,1.000000
3,2,-1,-1,-1,-1,-1,-1,-1,-1,-1,1.000000
3,3,-1,-1,-1,-1,-1,-1,-1,-1,-1,1.000000
2,0,1.000000,0.000000,0.999900,0.000100,1,1,0.000000,0.250000,0.749950,0.250000
2,1,1.000000,0.000000,0.999900,0.000100,0,1,0.000000,0.250000,0.749950,0.250000
2,2,1.000000,0.000000,0.999900,0.000100,1,1,0.000000,0.250000,0.749950,0.250000
2,3,1.000000,0.000000,0.999900,0.000100,1,1,0.000000,0.250000,0.749950,0.250000
1,0,1.000000,0.000000,0.999900,0.000100,0,1,0.000000,0.250000,0.749950,0.250000
1,1,1.000000,0.000000,0.999900,0.000100,1,1,0.000000,0.250000,0.749950,0.250000
1,2,1.000000,0.000000,0.999900,0.000100,0,1,0.000000,0.250000,0.749950,0.250000
1,3,1.000000,0.000000,0.999900,0.000100,0,1,0.000000,0.250000,0.749950,0.250000
0,0,1.000000,0.000000,0.999900,0.000100,1,0,0.000000,0.250000,0.749950,0.250000
0,1,1.000000,0.000000,0.999900,0.000100,0,0,0.000000,0.250000,0.749950,0.250000
0,2,1.000000,0.000000,0.999900,0.000100,1,0,0.000000,0.250000,0.749950,0.250000
0,3,1.000000,0.000000,0.999900,0.000100,1,0,0.000000,0.250000,0.749950,0.250000
"""


def convert_to_numpy(matrix_text):
"""
Converts a matrix in text to numpy and returns it.
"""
x = np.loadtxt(io.StringIO(matrix_text), skiprows=1, delimiter=",")
for i in np.arange(x.shape[0]):
# Check that switch and non-switch probabilities sum to 1
assert (x[i, 2] + x[i, 3]) == 1 or x[i, 2] == -1
# Check that non-mismatch and mismatch probabilities sum to 1
assert (x[i, 4] + x[i, 5]) == 1 or x[i, 4] == -1
return x[:, -1].reshape((4, 4)) # size (m, h)


def get_forward_backward_matrices():
fwd_matrix_1 = convert_to_numpy(_fwd_matrix_text_1)
bwd_matrix_1 = convert_to_numpy(_bwd_matrix_text_1)
fwd_matrix_2 = convert_to_numpy(_fwd_matrix_text_2)
bwd_matrix_2 = convert_to_numpy(_bwd_matrix_text_2)
return [fwd_matrix_1, bwd_matrix_1, fwd_matrix_2, bwd_matrix_2]


def get_test_data(matrix_text, par):
"""Extracts data for checking forward or backward probability matrix calculations."""
x = convert_to_numpy(matrix_text)
if par == "switch":
# Switch probability, one per site
return x[:, 2].reshape((4, 4))[:, 0]
elif par == "mismatch":
# Mismatch probability, one per site
return x[:, 4].reshape((4, 4))[:, 0]
elif par == "ref_hap_allele":
# Allele in haplotype in reference panel
# 0 = ref allele, 1 = alt allele
return x[:, 6].reshape((4, 4))
elif par == "query_hap_allele":
# Allele in haplotype in query
# 0 = ref allele, 1 = alt allele
return x[:, 7].reshape((4, 4))[:, 0]
elif par == "shift":
# Shift factor, one per site
return x[:, 8].reshape((4, 4))[:, 0]
elif par == "scale":
# Scale factor, one per site
return x[:, 9].reshape((4, 4))[:, 0]
elif par == "sum":
# Sum of values over haplotypes
return x[:, 10].reshape((4, 4))[:, 0]
else:
raise ValueError(f"Unknown parameter: {par}")

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