我想根據堆棧溢出帖子中的第二個列表對列表進行排序。就我而言，我的代碼試圖按Chromo對象對它們進行排序fitness_weights，因此我嘗試了鏈接帖子上的解決方案：def foobar(): ... chromolist = [x for _, x in sorted(zip(fitness_weights, chromolist))] ...給出錯誤：TypeError: '<' not supported between instances of 'Chromo' and 'Chromo'調試我試過：def foobar(): ... try: chromolist = [x for _, x in sorted(zip(fitness_weights, chromolist))] except Exception as e: print(fitness_weights) print(chromolist) print([i for i in zip(fitness_weights, chromolist)]) raise e print('works fine') ...輸出：works fineworks fineworks fineworks fineworks fineworks fineworks fineworks fineworks fineworks fineworks fineworks fineworks fineworks fineworks fineworks fineworks fineworks fineworks fineworks fineworks fineworks fine[2630793242, 2662598634, 1204127226, 1218205610, 1224753838, 1212750850, 1212293610, 1221507266, 1269226518, 1363578674, 1209661338, 2674408754, 1179213986, 1209887778, 2281636710, 1906925334, 1156258126, 1287144442, 1218205610, 1256241498, 2926198286, 1533442630, 1587421406, 2685579290, 1203563674, 1205066274, 1181576990, 1188462746, 1127834446, 2295554650, 1216261042, 1193222146, 1191591394, 1206052810, 1206800842, 1213410890, 1202786310, 1230097202, 1277296358, 1218982810][Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object, Chromo Object]這令人困惑，因為：所有數據類型均正確該功能正常工作 22 次我該如何解決？
1 回答
慕運維8079593
TA貢獻1876條經驗 獲得超5個贊
當您有兩個(weight, chromo)權重相等的對時會發生錯誤，此時 Python 會嘗試比較這些chromo值：
>>> class Chromo:
... pass
...
>>> chromolist = [Chromo(), Chromo()]
>>> fitness_weights = [42, 42]
>>> sorted(zip(fitness_weights, chromolist))
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: '<' not supported between instances of 'Chromo' and 'Chromo'
您可以通過使用僅提取權重的自定義排序鍵，或者通過添加對排序序列中的每個值都是唯一的 tie 斷路器來避免此問題，例如計數器：
from itertools import count
chromolist = [x for *_, x in sorted(zip(fitness_weights, count(), chromolist))]
計數器只是為了確保 Python 從不查看Chromo實例，因為現在每個元素都是一個(weight, unique_integer, Chromo)元組：
>>> from itertools import count
>>> sorted(zip(fitness_weights, count(), chromolist))
[(42, 0, <__main__.Chromo object at 0x1038cfa00>), (42, 1, <__main__.Chromo object at 0x103a396d0>)]
排序鍵只是一個生成要比較的值的函數，您可以使用 lambda ( lambda t: t[0]) 或operator.itemgetter()object：
from operator import itemgetter
chromolist = [x for _, x in sorted(zip(fitness_weights, chromolist), key=itemgetter(0))]
key 函數需要單獨遍歷輸入列表，因此速度會稍微慢一些，如這個包含 200 個輸入的簡單計時賽所示：
>>> from timeit import timeit
>>> fw = fitness_weights * 100
>>> cl = chromolist * 100
>>> timeit('sorted(zip(fw, count(), cl))', globals=globals(), number=100000)
1.4618491119981627
>>> timeit('sorted(zip(fw, cl), key=itemgetter(0))', globals=globals(), number=100000)
1.6409574589997646
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