def fitch_map_mutations(tree, genotypes, alleles):
"""
Returns the Fitch parsimony reconstruction for the specified set of genotypes.
The reconstruction is specified by returning the ancestral state and a
list of mutations on the tree. Each mutation is a (node, parent, state)
triple, where node is the node over which the transition occurs, the
parent is the index of the parent transition above it on the tree (or -1
if there is none) and state is the new state.
"""
genotypes = np.array(genotypes)
# Encode the set operations using a numpy array.
not_missing = genotypes != -1
if np.sum(not_missing) == 0:
raise ValueError("Must have at least one non-missing genotype")
num_alleles = np.max(genotypes[not_missing]) + 1
A = np.zeros((tree.num_nodes, num_alleles), dtype=np.int8)
for allele, u in zip(genotypes, tree.tree_sequence.samples()):
if allele != -1:
A[u, allele] = 1
else:
A[u] = 1
for u in tree.nodes(order="postorder"):
if not tree.is_sample(u):
A[u] = 1
for v in tree.children(u):
A[u] = np.logical_and(A[u], A[v])
if np.sum(A[u]) == 0:
for v in tree.children(u):
A[u] = np.logical_or(A[u], A[v])
root_states = np.zeros_like(A[0])
for root in tree.roots:
root_states = np.logical_or(root_states, A[root])
ancestral_state = np.where(root_states == 1)[0][0]
mutations = []
state = {}
for root in tree.roots:
state[root] = ancestral_state
parent = tskit.NULL
if A[root, ancestral_state] != 1:
state[root] = np.where(A[root] == 1)[0][0]
mutations.append(tskit.Mutation(
node=root, parent=tskit.NULL, derived_state=alleles[state[root]]))
parent = len(mutations) - 1
stack = [(root, parent)]
while len(stack) > 0:
u, parent_mutation = stack.pop()
for v in tree.children(u):
state[v] = state[u]
if A[v, state[u]] != 1:
state[v] = np.where(A[v] == 1)[0][0]
mutations.append(tskit.Mutation(
node=v, parent=parent_mutation, derived_state=alleles[state[v]]))
stack.append((v, len(mutations) - 1))
else:
stack.append((v, parent_mutation))
return alleles[ancestral_state], mutations
def test_mutation_over_0_5(self):
# Bug reported in https://github.com/tskit-dev/tskit/issues/987
genotypes = [1, 0, 0, 0, 0, 1]
ancestral_state, transitions = self.do_map_mutations(
self.tree, genotypes)
assert ancestral_state == "0"
assert len(transitions) == 2
assert transitions[0] == tskit.Mutation(node=0, derived_state="1")
assert transitions[1] == tskit.Mutation(node=5, derived_state="1")
def test_multi_mutation_missing_data(self):
genotypes = [1, 2, -1, 0, 0]
ancestral_state, transitions = self.do_map_mutations(self.tree, genotypes)
self.assertEqual(ancestral_state, "0")
self.assertEqual(len(transitions), 2)
self.assertEqual(
transitions[0], tskit.Mutation(node=5, parent=-1, derived_state="1"))
self.assertEqual(
transitions[1], tskit.Mutation(node=1, parent=0, derived_state="2"))
def test_mutation_over_7_0(self):
genotypes = [2, 1, 0, 0, 1]
ancestral_state, transitions = self.do_map_mutations(self.tree, genotypes)
self.assertEqual(ancestral_state, "0")
self.assertEqual(len(transitions), 2)
self.assertEqual(
transitions[0], tskit.Mutation(node=7, parent=-1, derived_state="1"))
self.assertEqual(
transitions[1], tskit.Mutation(node=0, parent=0, derived_state="2"))
def test_three_states_freq_n_minus_2(self, n):
tree = tskit.Tree.generate_star(n)
genotypes = np.zeros(n, dtype=np.int8)
genotypes[0] = 1
genotypes[1] = 2
ancestral_state, transitions = self.do_map_mutations(tree, genotypes)
assert ancestral_state == "0"
assert len(transitions) == 2
assert transitions[0] == tskit.Mutation(node=1, derived_state="2")
assert transitions[1] == tskit.Mutation(node=0, derived_state="1")
def test_three_clades(self):
genotypes = np.zeros(27, dtype=int)
genotypes[9:18] = 1
genotypes[18:27] = 2
ancestral_state, transitions = self.do_map_mutations(
self.tree, genotypes)
assert ancestral_state == "0"
assert len(transitions) == 2
assert transitions[0] == tskit.Mutation(node=38, derived_state="2")
assert transitions[1] == tskit.Mutation(node=34, derived_state="1")
def test_nonzero_ancestral_state(self):
genotypes = np.ones(27, dtype=int)
genotypes[0] = 0
genotypes[26] = 0
ancestral_state, transitions = self.do_map_mutations(
self.tree, genotypes)
assert ancestral_state == "1"
assert len(transitions) == 2
assert transitions[0] == tskit.Mutation(node=26, derived_state="0")
assert transitions[1] == tskit.Mutation(node=0, derived_state="0")
def test_mutation_over_7_back_mutation_4(self):
genotypes = [1, 0, 1, 0, 0, 1]
ancestral_state, transitions = self.do_map_mutations(
self.tree, genotypes)
assert ancestral_state == "0"
assert len(transitions) == 2
assert transitions[0] == tskit.Mutation(node=7, derived_state="1")
assert transitions[1] == tskit.Mutation(node=4,
derived_state="0",
parent=0)
def test_mutation_over_7_0_alleles(self):
genotypes = [2, 1, 0, 0, 1]
alleles = ["ANC", "ONE", "TWO"]
ancestral_state, transitions = self.do_map_mutations(
self.tree, genotypes, alleles)
self.assertEqual(ancestral_state, "ANC")
self.assertEqual(len(transitions), 2)
self.assertEqual(
transitions[0], tskit.Mutation(node=7, parent=-1, derived_state="ONE"))
self.assertEqual(
transitions[1], tskit.Mutation(node=0, parent=0, derived_state="TWO"))
def test_multi_mutation_missing_data(self):
genotypes = [1, 2, -1, 0, 0]
ancestral_state, transitions = self.do_map_mutations(
self.tree, genotypes)
assert ancestral_state == "0"
assert len(transitions) == 2
assert transitions[0] == tskit.Mutation(node=5,
parent=-1,
derived_state="1")
assert transitions[1] == tskit.Mutation(node=1,
parent=0,
derived_state="2")
def test_mutation_over_7_0_alleles(self):
genotypes = [2, 1, 0, 0, 1]
alleles = ["ANC", "ONE", "TWO"]
ancestral_state, transitions = self.do_map_mutations(
self.tree, genotypes, alleles)
assert ancestral_state == "ANC"
assert len(transitions) == 2
assert transitions[0] == tskit.Mutation(node=7,
parent=-1,
derived_state="ONE")
assert transitions[1] == tskit.Mutation(node=0,
parent=0,
derived_state="TWO")
def test_mutation_over_27_29(self):
genotypes = np.zeros(27, dtype=int)
genotypes[0:3] = 1
genotypes[6:9] = 1
ancestral_state, transitions = self.do_map_mutations(
self.tree, genotypes)
assert ancestral_state == "0"
assert len(transitions) == 2
# the algorithm chooses a back mutation instead
assert transitions[0] == tskit.Mutation(node=30, derived_state="1")
assert transitions[1] == tskit.Mutation(node=28,
derived_state="0",
parent=0)
def test_mutation_over_0_missing_data_4(self):
genotypes = [1, 0, 0, 0, -1]
ancestral_state, transitions = self.do_map_mutations(self.tree, genotypes)
self.assertEqual(ancestral_state, "0")
self.assertEqual(len(transitions), 1)
self.assertEqual(
transitions[0], tskit.Mutation(node=0, parent=-1, derived_state="1"))
def test_mutation_over_6(self):
genotypes = [1, 0, 1, 0, 1, 0]
ancestral_state, transitions = self.do_map_mutations(
self.tree, genotypes)
assert ancestral_state == "0"
assert len(transitions) == 1
assert transitions[0] == tskit.Mutation(node=6, derived_state="1")
def test_mutation_over_0_missing_data_4(self):
genotypes = [1, 0, 0, 0, -1]
ancestral_state, transitions = self.do_map_mutations(
self.tree, genotypes)
assert ancestral_state == "0"
assert len(transitions) == 1
assert transitions[0] == tskit.Mutation(node=0,
parent=-1,
derived_state="1")
def test_missing_data(self, n):
tree = tskit.Tree.generate_star(n)
genotypes = np.zeros(n, dtype=np.int8)
genotypes[0] = tskit.MISSING_DATA
genotypes[1] = 1
ancestral_state, transitions = self.do_map_mutations(tree, genotypes)
assert ancestral_state == "0"
assert len(transitions) == 1
assert transitions[0] == tskit.Mutation(node=1, derived_state="1")
def make_mutation(id_):
site, node, derived_state, parent, metadata = tree_sequence.get_mutation(
id_)
return tskit.Mutation(id_=id_,
site=site,
node=node,
derived_state=derived_state,
parent=parent,
metadata=metadata)
def make_mutation(id_):
site, node, derived_state, parent, metadata = ll_ts.get_mutation(id_)
return tskit.Mutation(
id_=id_,
site=site,
node=node,
derived_state=derived_state,
parent=parent,
metadata=metadata,
)
def test_mutation_over_leaf_sibling_missing(self):
genotypes = [0, 0, 1, -1, 0]
ancestral_state, transitions = self.do_map_mutations(self.tree, genotypes)
self.assertEqual(ancestral_state, "0")
self.assertEqual(len(transitions), 1)
# We assume that the mutation is over the parent of 2 and the missing data
# so we impute that 3 also has allele 1. This suprising behaviour to me:
# I would have thought it was more parsimonious to assume that the missing
# data had the ancestral state. However, the number of *state changes*
# is the same, which is what the algorithm is minimising.
self.assertEqual(
transitions[0], tskit.Mutation(node=6, parent=-1, derived_state="1"))
# Reverse is the same
genotypes = [0, 0, -1, 1, 0]
ancestral_state, transitions = self.do_map_mutations(self.tree, genotypes)
self.assertEqual(ancestral_state, "0")
self.assertEqual(len(transitions), 1)
self.assertEqual(
transitions[0], tskit.Mutation(node=6, parent=-1, derived_state="1"))
def make_mutation(id_):
site, node, derived_state, parent, metadata = ll_ts.get_mutation(
id_)
return tskit.Mutation(
id_=id_,
site=site,
node=node,
derived_state=derived_state,
parent=parent,
encoded_metadata=metadata,
metadata_decoder=tskit.metadata.parse_metadata_schema(
ll_ts.get_table_metadata_schemas().mutation).decode_row,
)
def hartigan_map_mutations(tree, genotypes, alleles):
"""
Returns a Hartigan parsimony reconstruction for the specified set of genotypes.
The reconstruction is specified by returning the ancestral state and a
list of mutations on the tree. Each mutation is a (node, parent, state)
triple, where node is the node over which the transition occurs, the
parent is the index of the parent transition above it on the tree (or -1
if there is none) and state is the new state.
"""
genotypes = np.array(genotypes)
not_missing = genotypes != -1
if np.sum(not_missing) == 0:
raise ValueError("Must have at least one non-missing genotype")
num_alleles = np.max(genotypes[not_missing]) + 1
num_nodes = tree.tree_sequence.num_nodes
# use a numpy array of 0/1 values to represent the set of states
# to make the code as similar as possible to the C implementation.
optimal_set = np.zeros((num_nodes + 1, num_alleles), dtype=np.int8)
for allele, u in zip(genotypes, tree.tree_sequence.samples()):
if allele != -1:
optimal_set[u, allele] = 1
else:
optimal_set[u] = 1
allele_count = np.zeros(num_alleles, dtype=int)
for root in tree.roots:
for u in tree.nodes(root, order="postorder"):
allele_count[:] = 0
for v in tree.children(u):
for j in range(num_alleles):
allele_count[j] += optimal_set[v, j]
if not tree.is_sample(u):
max_allele_count = np.max(allele_count)
optimal_set[u, allele_count == max_allele_count] = 1
allele_count[:] = 0
for v in tree.roots:
for j in range(num_alleles):
allele_count[j] += optimal_set[v, j]
max_allele_count = np.max(allele_count)
optimal_root_set = np.zeros(num_alleles, dtype=int)
optimal_root_set[allele_count == max_allele_count] = 1
ancestral_state = np.argmax(optimal_root_set)
@attr.s
class StackElement:
node = attr.ib()
state = attr.ib()
mutation_parent = attr.ib()
mutations = []
for root in tree.roots:
stack = [StackElement(root, ancestral_state, -1)]
while len(stack) > 0:
s = stack.pop()
if optimal_set[s.node, s.state] == 0:
s.state = np.argmax(optimal_set[s.node])
mutation = tskit.Mutation(
node=s.node,
derived_state=alleles[s.state],
parent=s.mutation_parent,
)
s.mutation_parent = len(mutations)
mutations.append(mutation)
for v in tree.children(s.node):
stack.append(StackElement(v, s.state, s.mutation_parent))
return alleles[ancestral_state], mutations
