dost

Initial commit: greedy nearest-neighbour and total
dkl9

dkl9 commited on 2025-184 18:43:57
Showing 1 changed files, with 30 additions and 0 deletions.

main.py
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+import math
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+import typing
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+import collections.abc
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+
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+Func: typing.TypeAlias = collections.abc.Callable
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+DistTable: typing.TypeAlias = list[list[float]]
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+IndSeq: typing.TypeAlias = list[int]
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+
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+def distance_table[T](points: list[T], metric: Func[[T, T], float]) -> DistTable:
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+    return [[metric(x, y) for y in points] for x in points]
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+
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+def score_nearest(distances: DistTable, sample: IndSeq) -> float:
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+    return sum(min(distances[i][j] for j in sample) for i in range(len(distances)))
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+
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+def score_total(distances: DistTable, sample: IndSeq) -> float:
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+    return sum(sum(
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+        0 if i in sample else distances[i][j] for j in sample
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+    ) for i in range(len(distances)))
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+
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+def greedy_min_seq(distances: DistTable, score_func: Func[[DistTable, IndSeq], float]) -> IndSeq:
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+    seq = []
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+    options = set(range(len(distances)))
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+    while options:
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+        best = min(options, key=lambda o: score_func(distances, seq + [o]))
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+        seq.append(best)
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+        options.remove(best)
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+    return seq
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+
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+dt: DistTable = distance_table([(0, 2), (3, 2), (4, 2), (5, 0), (0, 0)], math.dist)
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+print(greedy_min_seq(dt, score_total))
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