Introduction
The Python class moarchiving.BiobjectiveNondominatedSortedList implements a bi-objective non-dominated archive with list as parent class. It is heavily based on the bisect module. It provides easy and fast access to the overall hypervolume, the contributing hypervolume of each element, and to the uncrowded hypervolume improvement of any given point in objective space.
Installation
Either simply via
pip install moarchiving
or from GitHub via
pip install git+https://github.com/CMA-ES/moarchiving.git@master
The single file moarchiving.py (from the moarchiving/ folder) can also be directly used by itself when copied in the current folder or in a path visible to Python (e.g. a path contained in sys.path).
Testing
python -m moarchiving.test
on a system shell should output something like
doctest.testmod(moarchiving.moarchiving)
TestResults(failed=0, attempted=77)
Usage
from moarchiving import BiobjectiveNondominatedSortedList as NDA
nda = NDA() # a new empty non-dominated archive
# add a pair to the list if non-dominated and removed dominated entries
nda.add([2, 1], info={'f': [2, 1], 'x': "don't know"})
nda == [[2, 1], ] # is True
nda.add([1, 1]) # dominates previous entry
nda.discarded == [[2, 1]] # just now removed element(s)
nda == [[1, 1]] # is TrueDetails
moarchiving uses the fractions.Fraction type to avoid rounding errors when computing hypervolume differences, but its usage can also easily be switched off by assigning the class attribute hypervolume_computation_float_type and hypervolume_final_float_type to float.
The Fraction type can become prohibitively computationally expensive with increasing
precision.
Releases
- 0.6.0 the
infosattribute is alistwith corresponding (arbitrary) information, e.g. for keeping the respective solutions. - 0.5.3 fixed assertion error when not using
fractions.Fraction - 0.5.2 first published version
Links
- Code on Github
- Documentation (possibly slightly outdated) in
