Commit c0d4c04c authored by Philipp Arras's avatar Philipp Arras
Browse files

Add Laplace distribution

parent 9520f5af
Pipeline #92460 passed with stages
in 11 minutes and 7 seconds
...@@ -77,7 +77,8 @@ from .sugar import * ...@@ -77,7 +77,8 @@ from .sugar import *
from .plot import Plot from .plot import Plot
from .library.special_distributions import InverseGammaOperator, UniformOperator from .library.special_distributions import (InverseGammaOperator, UniformOperator,
LaplaceOperator)
from .library.los_response import LOSResponse from .library.los_response import LOSResponse
from .library.dynamic_operator import (dynamic_operator, from .library.dynamic_operator import (dynamic_operator,
dynamic_lightcone_operator) dynamic_lightcone_operator)
......
...@@ -17,7 +17,7 @@ ...@@ -17,7 +17,7 @@
import numpy as np import numpy as np
from scipy.interpolate import CubicSpline from scipy.interpolate import CubicSpline
from scipy.stats import invgamma, norm from scipy.stats import invgamma, norm, laplace
from .. import random from .. import random
from ..domain_tuple import DomainTuple from ..domain_tuple import DomainTuple
...@@ -158,3 +158,29 @@ class UniformOperator(Operator): ...@@ -158,3 +158,29 @@ class UniformOperator(Operator):
def inverse(self, field): def inverse(self, field):
res = norm._ppf(field.val/self._scale - self._loc) res = norm._ppf(field.val/self._scale - self._loc)
return Field(field.domain, res) return Field(field.domain, res)
def LaplaceOperator(domain, alpha, delta=1e-2):
"""Transforms a Gaussian with unit covariance and zero mean into a
Laplacian distribution.
The pdf of the laplace distribution is defined as follows:
.. math::
\\frac{\\alpha}{2} \\exp \\left(-\\alpha |x| \\right)
This transformation is implemented as a spline interpolation which maps a
Gaussian onto a Laplace distribution.
Parameters
----------
domain : Domain, tuple of Domain or DomainTuple
The domain on which the field shall be defined. This is at the same
time the domain and the target of the operator.
alpha : float
The alpha-parameter of the Laplace distribution.
delta : float
Distance between sampling points for spline interpolation.
"""
return _InterpolationOperator(domain, lambda x: laplace.ppf(norm._cdf(x), float(alpha)),
-8.2, 8.2, delta)
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