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lammps/tools/i-pi/ipi/inputs/prng.py
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"""Deals with creating the random number generator.
Copyright (C) 2013, Joshua More and Michele Ceriotti
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http.//www.gnu.org/licenses/>.
Generates a random number generator either from a seed number, or from a
state vector.
Classes:
InputRandom: Deals with creating the Random object from a file, and
writing the checkpoints.
"""
__all__ = ['InputRandom']
import numpy as np
from ipi.utils.prng import *
from ipi.utils.inputvalue import *
class InputRandom(Input):
"""Random input class.
Handles generating the appropriate random number class from the xml
input file, and generating the xml checkpoint tags and data from an
instance of the object.
Attributes:
seed: An optional integer giving a seed to initialise the random number
generator from. Defaults to 123456.
state: An optional array giving the state of the random number generator.
Defaults to an empty array.
has_gauss: An optional integer giving whether there is a stored
Gaussian number or not. Defaults to 0.
gauss: An optional float giving the stored Gaussian number. Defaults to
0.0.
set_pos: An optional integer giving the position in the state array
that is being read from. Defaults to 0.
"""
fields = {"seed" : (InputValue, {"dtype" : int,
"default" : 123456,
"help" : "This is the seed number used to generate the initial state of the random number generator."}),
"state" : (InputArray, {"dtype" : np.uint,
"default" : input_default(factory=np.zeros, kwargs={'shape': (0,), 'dtype': np.uint}),
"help" : "Gives the state vector for the random number generator. Avoid directly modifying this unless you are very familiar with the inner workings of the algorithm used."}),
"has_gauss" : (InputValue, {"dtype" : int,
"default" : 0,
"help" : "Determines whether there is a stored gaussian number or not. A value of 0 means there is none stored."}),
"gauss" : (InputValue, {"dtype" : float,
"default" : 0.00,
"help" : "The stored Gaussian number." }),
"set_pos" : (InputValue, {"dtype" : int,
"default" : 0,
"help" : "Gives the position in the state array that the random number generator is reading from."})}
default_help = "Deals with the pseudo-random number generator."
default_label = "PRNG"
def store(self, prng):
"""Takes a random number instance and stores a minimal
representation of it.
Args:
prng: A random number object from which to initialise from.
"""
super(InputRandom,self).store(prng)
self.seed.store(prng.seed)
gstate = prng.state
self.state.store(gstate[1])
self.set_pos.store(gstate[2])
self.has_gauss.store(gstate[3])
self.gauss.store(gstate[4])
def fetch(self):
"""Creates a random number object.
Returns:
An random number object of the appropriate type and with the
appropriate properties given the attributes of the InputRandom
object.
"""
super(InputRandom,self).fetch()
if not self.state._explicit:
return Random(seed=self.seed.fetch())
else:
return Random(state=('MT19937',self.state.fetch(), self.set_pos.fetch(), self.has_gauss.fetch(), self.gauss.fetch() ))
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