Class Distributor<K>

java.lang.Object
org.jgrapht.generate.netgen.Distributor<K>
Type Parameters:
K - the element type.
public class Distributor<K> extends Object
Distributes value units among keys given lower and upper bound constraints.

Let's define a set of elements $\{k_1, k_2, \dots, k_n\}$. For every element a set of lower bounds $\{l_1, l_2, \dots, l_t\}$ and upper bounds $\{u_1, u_2, \dots, u_p\}$ is specified. The problem is to randomly distribute a number of abstract value units $V$ among keys such that the lower bound and upper bound constraints are satisfied. This class solves this problem.

See Also:

  • Field Details

    • rng

      private final Random rng
      Random number generator used by this distributor.

    • lowerBounds

      private final List<Function<K,Integer>> lowerBounds
      Lower bounds.

    • upperBounds

      private final List<Function<K,Integer>> upperBounds
      Upper bounds.

  • Constructor Details

    • Distributor

      public Distributor()
      Creates a Distributor using random seed.

    • Distributor

      public Distributor(long seed)
      Creates a distributor using the specified seed.
      Parameters:
      seed - the seed for the random number generator.

    • Distributor

      public Distributor(Random rng)
      Creates a distributor which uses the random number generatow rng.
      Parameters:
      rng - a random number generator to use.

  • Method Details

    • addUpperBound

      public void addUpperBound(Function<K,Integer> upperBound)
      Adds an upper bounding function. This function must be defined for all keys.
      Parameters:
      upperBound - an upper bound function.

    • addLowerBound

      public void addLowerBound(Function<K,Integer> lowerBound)
      Adds a lower bound function. This function must be defined for all keys.
      Parameters:
      lowerBound - a lower bound function.

    • computeLowerBounds

      private List<Integer> computeLowerBounds(List<K> keys)
      Finds a maximum lower bound for every key.
      Parameters:
      keys - list of keys.
      Returns:
      the computed key lower bounds.

    • computeUpperBounds

      private List<Integer> computeUpperBounds(List<K> keys)
      Finds a minimum lower bound for every key.
      Parameters:
      keys - a list of keys.
      Returns:
      the computed key upper bound.

    • computeSuffixSum

      private Pair<List<Integer>, Long> computeSuffixSum(List<Integer> bounds)
      Computes a suffix sum of the bounds. Returns computed suffix sum and the sum of all elements in the bounds list.
      Parameters:
      bounds - list of integers.
      Returns:
      computed pair of suffix sum list and a sum of all elements.

    • getDistribution

      public List<Integer> getDistribution(List<K> keys, int valueNum)
      Computes and returns a value distribution for the list of keys. The resulting distribution will satisfy the (possibly empty) sets of lower and upper bound constraints. Distributed values will be in the same order as the keys in the key list.
      Parameters:
      keys - the list of keys.
      valueNum - the number of abstract value units to distribute.
      Returns:
      the computed value distribution.