wehub-resource-sync
161 lines
3.5 KiB
Python
161 lines
3.5 KiB
Python
from easygraph.utils.decorators import *
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__all__ = [
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"is_connected",
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"number_connected_components",
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"connected_components",
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"connected_components_directed",
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"connected_component_of_node",
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]
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@not_implemented_for("multigraph")
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def is_connected(G):
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"""Returns whether the graph is connected or not.
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Parameters
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----------
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G : easygraph.Graph or easygraph.DiGraph
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Returns
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-------
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is_biconnected : boolean
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`True` if the graph is connected.
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Examples
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--------
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>>> is_connected(G)
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"""
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assert len(G) != 0, "No node in the graph."
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arbitrary_node = next(iter(G)) # Pick an arbitrary node to run BFS
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return len(G) == sum(1 for node in _plain_bfs(G, arbitrary_node))
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@not_implemented_for("multigraph")
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def number_connected_components(G):
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"""Returns the number of connected components.
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Parameters
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----------
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G : easygraph.Graph
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Returns
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-------
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number_connected_components : int
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The number of connected components.
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Examples
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--------
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>>> number_connected_components(G)
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"""
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return sum(1 for component in _generator_connected_components(G))
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@not_implemented_for("multigraph")
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@hybrid("cpp_connected_components_undirected")
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def connected_components(G):
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"""Returns a list of connected components, each of which denotes the edges set of a connected component.
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Parameters
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----------
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G : easygraph.Graph
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Returns
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-------
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connected_components : list of list
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Each element list is the edges set of a connected component.
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Examples
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--------
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>>> connected_components(G)
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"""
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seen = set()
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for v in G:
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if v not in seen:
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c = set(_plain_bfs(G, v))
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seen.update(c)
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yield c
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@not_implemented_for("multigraph")
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@hybrid("cpp_connected_components_directed")
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def connected_components_directed(G):
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"""Returns a list of connected components, each of which denotes the edges set of a connected component.
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Parameters
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----------
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G : easygraph.DiGraph
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Returns
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-------
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connected_components : list of list
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Each element list is the edges set of a connected component.
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Examples
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--------
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>>> connected_components(G)
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"""
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seen = set()
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for v in G:
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if v not in seen:
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c = set(_plain_bfs(G, v))
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seen.update(c)
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yield c
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def _generator_connected_components(G):
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seen = set()
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for v in G:
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if v not in seen:
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component = set(_plain_bfs(G, v))
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yield component
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seen.update(component)
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@not_implemented_for("multigraph")
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def connected_component_of_node(G, node):
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"""Returns the connected component that *node* belongs to.
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Parameters
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----------
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G : easygraph.Graph
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node : object
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The target node
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Returns
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-------
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connected_component_of_node : set
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The connected component that *node* belongs to.
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Examples
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--------
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Returns the connected component of one node `Jack`.
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>>> connected_component_of_node(G, node='Jack')
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"""
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return set(_plain_bfs(G, node))
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@hybrid("cpp_plain_bfs")
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def _plain_bfs(G, source):
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"""
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A fast BFS node generator
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"""
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G_adj = G.adj
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seen = set()
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nextlevel = {source}
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while nextlevel:
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thislevel = nextlevel
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nextlevel = set()
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for v in thislevel:
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if v not in seen:
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yield v
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seen.add(v)
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nextlevel.update(G_adj[v])
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