Opened 13 years ago
Last modified 13 years ago
#1496 closed feature request
Implement generalized rank selection operator — at Version 4
Reported by: | abeham | Owned by: | abeham |
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Priority: | high | Milestone: | HeuristicLab 3.3.5 |
Component: | Selection | Version: | 3.3.5 |
Keywords: | Cc: |
Description (last modified by abeham)
I just read about a generalized rank selection operator which allows a stepless variation of the selection pressure and that is based on the idea of rank selection.
The operator is described in Tate1995 as follows: "Instead, we selected parent strings by choosing a uniform random number between 1 and sqrt(m) (where m is the population size), then squaring it. The result was truncated and taken to be the rank of the selected parent (where string zero is the fittest string in the population). This approach can be generalized to give an arbitrary degree of preference or even varied dynamically during a given run by changing the power of the root of m during subsequent generations."
Unfortunately the authors did not name this operator, so my idea would be to call it GeneralizedRankSelection
The formula for calculating the index of the selected solution (assuming the solutions are sorted from best to worst) thus is as follows:
double randomNumber = 1 + rand() * (pow(m, 1.0 / pressure) - 1); int selectedIndex = floor(pow(randomNumber, pressure) - 1);
The variable pressure lies in the open interval [1;infinity). If pressure equals 1, this is similar to random selection. The higher pressure becomes, the more likely better solutions are selected.
Change History (4)
comment:1 Changed 13 years ago by abeham
- Description modified (diff)
- Owner changed from swagner to abeham
- Status changed from new to assigned
comment:2 Changed 13 years ago by abeham
- Description modified (diff)
comment:3 Changed 13 years ago by abeham
- Status changed from assigned to accepted
comment:4 Changed 13 years ago by abeham
- Description modified (diff)
r6081