or-tools - SetGlobalSpanCoefficient 方法谷歌或工具

Question

我正在尝试使用谷歌或工具解决车辆路线问题。
这是链接https://developers.google.com/optimization/routing/vrp .
我正在尝试使用 google 的代码，但是当我遇到这段代码时:

def add_distance_dimension(routing, distance_callback):
  """Add Global Span constraint"""
  distance = 'Distance'
  maximum_distance = 3000  # Maximum distance per vehicle.
  routing.AddDimension(
      distance_callback,
      0,  # null slack
      maximum_distance,
      True,  # start cumul to zero
      distance)
  distance_dimension = routing.GetDimensionOrDie(distance)
  # Try to minimize the max distance among vehicles.
  distance_dimension.SetGlobalSpanCostCoefficient(100)

我不明白最后一个结构的含义

distance_dimension.SetGlobalSpanCostCoefficient(100)

这个函数的目的是什么，参数的含义是什么？为什么那里有一个“100”？

Answer 1

documentation ，自发布此问题以来很可能已经更新，阐明了 100 的含义:

The method SetGlobalSpanCostCoefficient sets a large coefficient (100) for the global span of the routes, which in this example is the maximum of the distances of the routes. This makes the global span the predominant factor in the objective function, so the program minimizes the length of the longest route.

一般来说(来自 API reference )，该方法

[sets] a cost proportional to the global dimension span, that is the difference between the largest value of route end cumul variables and the smallest value of route start cumul variables. In other words: global_span_cost = coefficient * (Max(dimension end value) - Min(dimension start value)).