Question

是否可以使用健身价值来评估人口中的每个人,而不会发现以下假代码的概率:

For all members of population
    sum += fitness ( member)
End for 
Loop until new population is full 
      Do this twice 
            Number = Random between 0 and sum
            Currentfitness = 0.0
            For each member in population
               Currentfitness += fitness (member)
               if Number > Currentfitness then select member
            End for 
      End
Create offspring 
End loop

代码的下一部分是做什么的?

Do this twice

我真的搞不懂轮轮轮轮轮如何选择双亲。有什么可以帮忙的吗?

Answer 1

代码意在选择随机元素,但概率取决于一定的重量。

示例:

We want to select from a two-element array with the following weights: { 1, 9 }
The cumulative weight is { 1, 10 }
The total weight is 10
We choose a random number between 1 and 10
We look into the cumulative weight array and find the first index where our random number is greater than the element
This index is the index of the randomly chosen element

直观地说,这个例子是有道理的:随机数字的十倍中有九倍在1到9之间,导致第一个元素的概率为0.9(正视规定的重量)。

Answer 2

数字应小于/强小于当前,否则会严重偏向第一人口成员。

示例:

Consider weights {1, 2, 7}
Cumulative weights {1, 3, 10}
Total weight 10
Choose random double between 0 and 10 with r.NextDouble(10.0)
90% of time 1 is chosen with given pseudo code. Should be 10%

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