:py:mod:`nessai.utils.sampling`
===============================

.. py:module:: nessai.utils.sampling

.. autoapi-nested-parse::

   Utilities related to drawing samples.

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Module Contents
---------------


Functions
~~~~~~~~~

.. autoapisummary::

   nessai.utils.sampling.compute_radius
   nessai.utils.sampling.draw_surface_nsphere
   nessai.utils.sampling.draw_nsphere
   nessai.utils.sampling.draw_uniform
   nessai.utils.sampling.draw_gaussian
   nessai.utils.sampling.draw_truncated_gaussian



.. py:function:: compute_radius(n, q=0.95)

   
   Compute the radius that contains a fraction of the total probability          in an n-dimensional unit Gaussian.

   Uses the inverse CDF of a chi-distribution with n degrees of freedom.

   :Parameters:

       **n** : int
           Number of dimensions

       **q** : float
           Fraction of the total probability

   :Returns:

       float
           Radius













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.. py:function:: draw_surface_nsphere(dims, r=1, N=1000)

   
   Draw N points uniformly from  n-1 sphere of radius r using Marsaglia's
   algorithm. E.g for 3 dimensions returns points on a 'regular' sphere.

   See Marsaglia (1972)

   :Parameters:

       **dims** : int
           Dimension of the n-sphere

       **r** : float, optional
           Radius of the n-sphere, if specified it is used to rescale the samples

       **N** : int, optional
           Number of samples to draw

   :Returns:

       ndarray
           Array of samples with shape (N, dims)













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.. py:function:: draw_nsphere(dims, r=1, N=1000, fuzz=1.0)

   
   Draw N points uniformly within an n-sphere of radius r


   :Parameters:

       **dims** : int
           Dimension of the n-sphere

       **r** : float, optional
           Radius of the n-ball

       **N** : int, optional
           Number of samples to draw

       **fuzz** : float, optional
           Fuzz factor by which to increase the radius of the n-ball

   :Returns:

       ndarray
           Array of samples with shape (N, dims)













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.. py:function:: draw_uniform(dims, r=(1, ), N=1000, fuzz=1.0)

   
   Draw from a uniform distribution on [0, 1].

   Deals with extra input parameters used by other draw functions

   :Parameters:

       **dims** : int
           Dimension of the n-sphere

       **r** : float, optional
           Radius of the n-ball. (Ignored by this function)

       **N** : int, ignored
           Number of samples to draw

       **fuzz** : float, ignored
           Fuzz factor by which to increase the radius of the n-ball. (Ignored by
           this function)

   :Returns:

       ndarraay
           Array of samples with shape (N, dims)













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.. py:function:: draw_gaussian(dims, r=1, N=1000, fuzz=1.0)

   
   Wrapper for numpy.random.randn that deals with extra input parameters
   r and fuzz


   :Parameters:

       **dims** : int
           Dimension of the n-sphere

       **r** : float, optional
           Radius of the n-ball

       **N** : int, ignored
           Number of samples to draw

       **fuzz** : float, ignored
           Fuzz factor by which to increase the radius of the n-ball

   :Returns:

       ndarray
           Array of samples with shape (N, dims)













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.. py:function:: draw_truncated_gaussian(dims, r, N=1000, fuzz=1.0, var=1)

   
   Draw N points from a truncated gaussian with a given a radius


   :Parameters:

       **dims** : int
           Dimension of the n-sphere

       **r** : float
           Radius of the truncated Gaussian

       **N** : int, ignored
           Number of samples to draw

       **fuzz** : float, ignored
           Fuzz factor by which to increase the radius of the truncated Gaussian

   :Returns:

       ndarray
           Array of samples with shape (N, dims)













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