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python - Python函数返回一个空列表

问题描述

所以，我有一个函数应该接受一个类实例列表，修改类实例列表，然后返回修改后的类实例。但是，即使在返回列表之前列表中有值，列表也将返回为空。代码贴在下面：

def calculate(self,solution_list):
    """
    Calculates the ranked fitness for the solution list.
    Returns the solution list with evaluated fitnesses.


    """

    Block_of_unimportant_code

    print("Ranked fitness solution")
    print(solution_list)
    return solution_list


print("Before I do fitness calculation")'''
print(solution_list)
solution_list = self.fitness.calculate(solution_list)
print("AFter fitness is calculated")
print(solution_list)

当我执行代码时，这是打印语句中给出的内容：

在我进行健身计算之前

[class_instance0x2aab3fdc4ed0, class_instance0x2aab3fdc0350, class_instance0x2aab3fdc7ed0, class_instance0x2aab3fdb4e10, class_instance0x2aab3fdcdc10, class_instance0x2aab3fdc4190, class_instance0x2aab3fdc9c90, class_instance0x2aab3fdd1b10, class_instance0x2aab3fdd87d0, class_instance0x2aab3fdd4a10, class_instance0x2aab3fdd6890, class_instance0x2aab3fdda710, class_instance0x2aaab4beb410, class_instance0x2aab3fddc650, class_instance0x2aab3fddf4d0, class_instance0x2aab3fdde590]

排名健身解决方案

[class_instance0x2aab3fdc4ed0, class_instance0x2aab3fdc0350, class_instance0x2aab3fdc7ed0, class_instance0x2aab3fdb4e10, class_instance0x2aab3fdcdc10, class_instance0x2aab3fdc4190, class_instance0x2aab3fdc9c90, class_instance0x2aab3fdd1b10, class_instance0x2aab3fdd87d0, class_instance0x2aab3fdd4a10, class_instance0x2aab3fdd6890, class_instance0x2aab3fdda710, class_instance0x2aaab4beb410, class_instance0x2aab3fddc650, class_instance0x2aab3fddf4d0, class_instance0x2aab3fdde590]

健身后计算

没有任何

因此，显然实例列表在被调用时具有值，在返回之前具有值，并且在返回后立即丢失它们，我真的不明白这是什么原因。

任何解决问题的反馈或建议将不胜感激。

标签： pythondebuggingmethodsnonetype

解决方案

你能发布完整的代码。另外，您确定要编写 self.fitness.calculate(solution_list) 吗？

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