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Diffstat (limited to '.venv/lib/python3.12/site-packages/networkx/generators/interval_graph.py')
-rw-r--r-- | .venv/lib/python3.12/site-packages/networkx/generators/interval_graph.py | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/.venv/lib/python3.12/site-packages/networkx/generators/interval_graph.py b/.venv/lib/python3.12/site-packages/networkx/generators/interval_graph.py new file mode 100644 index 00000000..6a3fda45 --- /dev/null +++ b/.venv/lib/python3.12/site-packages/networkx/generators/interval_graph.py @@ -0,0 +1,70 @@ +""" +Generators for interval graph. +""" + +from collections.abc import Sequence + +import networkx as nx + +__all__ = ["interval_graph"] + + +@nx._dispatchable(graphs=None, returns_graph=True) +def interval_graph(intervals): + """Generates an interval graph for a list of intervals given. + + In graph theory, an interval graph is an undirected graph formed from a set + of closed intervals on the real line, with a vertex for each interval + and an edge between vertices whose intervals intersect. + It is the intersection graph of the intervals. + + More information can be found at: + https://en.wikipedia.org/wiki/Interval_graph + + Parameters + ---------- + intervals : a sequence of intervals, say (l, r) where l is the left end, + and r is the right end of the closed interval. + + Returns + ------- + G : networkx graph + + Examples + -------- + >>> intervals = [(-2, 3), [1, 4], (2, 3), (4, 6)] + >>> G = nx.interval_graph(intervals) + >>> sorted(G.edges) + [((-2, 3), (1, 4)), ((-2, 3), (2, 3)), ((1, 4), (2, 3)), ((1, 4), (4, 6))] + + Raises + ------ + :exc:`TypeError` + if `intervals` contains None or an element which is not + collections.abc.Sequence or not a length of 2. + :exc:`ValueError` + if `intervals` contains an interval such that min1 > max1 + where min1,max1 = interval + """ + intervals = list(intervals) + for interval in intervals: + if not (isinstance(interval, Sequence) and len(interval) == 2): + raise TypeError( + "Each interval must have length 2, and be a " + "collections.abc.Sequence such as tuple or list." + ) + if interval[0] > interval[1]: + raise ValueError(f"Interval must have lower value first. Got {interval}") + + graph = nx.Graph() + + tupled_intervals = [tuple(interval) for interval in intervals] + graph.add_nodes_from(tupled_intervals) + + while tupled_intervals: + min1, max1 = interval1 = tupled_intervals.pop() + for interval2 in tupled_intervals: + min2, max2 = interval2 + if max1 >= min2 and max2 >= min1: + graph.add_edge(interval1, interval2) + return graph |