def in_degrees(g: Mapping):
"""
>>> g = dict(a='c', b='ce', c='abde', d='c', e=['c', 'z'], f={})
>>> assert dict(in_degrees(g)) == (
... {'a': 1, 'b': 1, 'c': 4, 'd': 1, 'e': 2, 'f': 0, 'z': 1}
... )
"""
return out_degrees(edge_reversed_graph(g))
def leaf_nodes(g: Mapping):
"""
>>> g = dict(a='c', b='ce', c='abde', d='c', e=['c', 'z'], f={})
>>> sorted(leaf_nodes(g))
['f', 'z']
Note that `f` is present: Isolated nodes are considered both as
root and leaf nodes both.
"""
return root_nodes(edge_reversed_graph(g))
def parents(g: Mapping, source: Iterable):
"""Set of all nodes (not in source) adjacent TO 'source' in 'g'
>>> g = {
... 0: [1, 2],
... 1: [2, 3, 4],
... 2: [1, 4],
... 3: [4]
... }
>>> parents(g, [2, 3])
{0, 1}
>>> parents(g, [0])
set()
"""
return children(edge_reversed_graph(g), source)
def descendants(g: Mapping, source: Iterable, _exclude_nodes=None):
"""Returns the set of all nodes reachable FROM `source` in `g`.
>>> g = {
... 0: [1, 2],
... 1: [2, 3, 4],
... 2: [1, 4],
... 3: [4]
... }
>>> descendants(g, [2, 3])
{1, 4}
>>> descendants(g, [4])
set()
"""
return ancestors(edge_reversed_graph(g), source, _exclude_nodes)
def predecessors(g: Mapping, node):
"""Iterator of nodes that have directed paths TO node
>>> g = {
... 0: [1, 2],
... 1: [2, 3, 4],
... 2: [1, 4],
... 3: [4]}
>>> set(predecessors(g, 4))
{0, 1, 2, 3}
>>> set(predecessors(g, 2))
{0, 1, 2}
>>> set(predecessors(g, 0))
set()
Notice that 2 is a predecessor of 2 here because of the presence
of a 2-1-2 directed path.
"""
yield from successors(edge_reversed_graph(g), node)