/usr/lib/python3/dist-packages/deap/tools/migration.py is in python3-deap 1.0.2.post2-2.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 | def migRing(populations, k, selection, replacement=None, migarray=None):
"""Perform a ring migration between the *populations*. The migration first
select *k* emigrants from each population using the specified *selection*
operator and then replace *k* individuals from the associated population
in the *migarray* by the emigrants. If no *replacement* operator is
specified, the immigrants will replace the emigrants of the population,
otherwise, the immigrants will replace the individuals selected by the
*replacement* operator. The migration array, if provided, shall contain
each population's index once and only once. If no migration array is
provided, it defaults to a serial ring migration (1 -- 2 -- ... -- n --
1). Selection and replacement function are called using the signature
``selection(populations[i], k)`` and ``replacement(populations[i], k)``.
It is important to note that the replacement strategy must select *k*
**different** individuals. For example, using a traditional tournament for
replacement strategy will thus give undesirable effects, two individuals
will most likely try to enter the same slot.
:param populations: A list of (sub-)populations on which to operate
migration.
:param k: The number of individuals to migrate.
:param selection: The function to use for selection.
:param replacement: The function to use to select which individuals will
be replaced. If :obj:`None` (default) the individuals
that leave the population are directly replaced.
:param migarray: A list of indices indicating where the individuals from
a particular position in the list goes. This defaults
to a ring migration.
"""
nbr_demes = len(populations)
if migarray is None:
migarray = list(range(1, nbr_demes)) + [0]
immigrants = [[] for i in range(nbr_demes)]
emigrants = [[] for i in range(nbr_demes)]
for from_deme in range(nbr_demes):
emigrants[from_deme].extend(selection(populations[from_deme], k))
if replacement is None:
# If no replacement strategy is selected, replace those who migrate
immigrants[from_deme] = emigrants[from_deme]
else:
# Else select those who will be replaced
immigrants[from_deme].extend(replacement(populations[from_deme], k))
for from_deme, to_deme in enumerate(migarray):
for i, immigrant in enumerate(immigrants[to_deme]):
indx = populations[to_deme].index(immigrant)
populations[to_deme][indx] = emigrants[from_deme][i]
__all__ = ['migRing']
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