Python：将额外的参数传递给 callable

Question

我有以下python代码：import networkx as nx def cost(i, j, d, value1, value2):    # some operation involving all these values    return cost# graph is a networkx graph# src, dst are integers# cost is a callable that is passed 3 values automatically i.e. src, dst and d # d is a dictionary of edge weightspath = nx.dijkstra_path(graph, src, dst, weight=cost)现在我想通过两个值value1，并value2给cost功能。该networkx文件表示，weight可以接受恰好3参数的调用。但我需要value1和value2进行计算。如何才能做到这一点？编辑 使用 functools 的解决方案效果很好。但是，我的函数在一个类中，如下所示：import networkx as nx import functoolsclass Myclass:    def cost(self, i, j, d, value2):        # some operation involving all these values        # also need self    # graph is a networkx graph    # src, dst are integers    # cost is a callable that is passed 3 values automatically i.e. src, dst and d     # d is a dictionary of edge weights    # path = nx.dijkstra_path(graph, src, dst, cost)    cost_partial = functools.partial(cost, self=self, value2=5)    path = nx.dijkstra_path(graph, src, dst, cost_partial)使用这种方法，nx.dijkstra_path坚持分配src给self. 因此解释器抱怨self分配了多个值。我需要 self 来计算成本。

Answer 1

这在很大程度上取决于value1和的含义value2。我建议添加一个可由 networkx 调用的包装器：

def cost_wrapper(i, j, d):

    value1 = 0  # set values as needed

    value2 = 1

    return cost(i, j, d, value1, value2)

并将其提供给 networkx：

path = nx.dijkstra_path(graph, src, dst, weight=cost_wrapper)

或者简单地使它们成为全局变量，而不是参数。