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""" Basic utilities for the GA package.
"""
from numpy import mean, std
from prng import prng
class GAError(Exception):
""" Error from the GA code.
"""
def nop(x):
""" Basic 'no-op' stub useful for interfaces which require a function.
"""
return x
def flip_coin(p):
""" Return True with probability p.
"""
return (prng.random() < p)
class empty_class:
""" Dummy class for cloning objects.
"""
pass
def shallow_clone(item):
""" Make a simple clone of an object.
The attributes are not copied, just referenced.
"""
new = empty_class()
new.__class__ = item.__class__
new.__dict__.update(item.__dict__)
return new
def remove_NaN(z):
""" Return an array with only finite (non-NaN, non-inf) values.
"""
from numpy import isfinite
return z[isfinite(z)]
def my_std(s):
""" Standard deviation robust to NaNs and infs.
"""
a = remove_NaN(s)
if len(a) > 1:
return std(a)
else:
return 0.
def my_mean(s):
""" Mean robust to NaNs and infs.
"""
a = remove_NaN(s)
if len(a) > 0:
return mean(a)
else:
return 0.
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