# autofit.LogGaussianPrior#

class LogGaussianPrior[source]#

Bases: Prior

A prior with a log base 10 uniform distribution, defined between a lower limit and upper limit.

The conversion of an input unit value, u, to a physical value, p, via the prior is as follows:

$p = \mu + (\sigma * sqrt(2) * erfcinv(2.0 * (1.0 - u))$

For example for prior = LogGaussianPrior(mean=1.0, sigma=2.0), an input prior.value_for(unit=0.5) is equal to 1.0.

[Rich describe how this is done via message]

Parameters
• mean (float) – The mean of the Gaussian distribution defining the prior.

• sigma (float) – The sigma value of the Gaussian distribution defining the prior.

• lower_limit (float) – A lower limit of the Gaussian distribution; physical values below this value are rejected.

• upper_limit (float) – A upper limit of the Gaussian distribution; physical values below this value are rejected.

Examples

prior = af.LogGaussianPrior(mean=1.0, sigma=2.0, lower_limit=0.0, upper_limit=2.0)

physical_value = prior.value_for(unit=0.5)

Methods

 assert_within_limits dict A dictionary representation of this prior for_class_and_attribute_name from_dict Returns a prior from a JSON representation. gaussian_prior_model_for_arguments has Does this instance have an attribute which is of type cls? instance_for_arguments make_indexes rtype Tuple[ndarray, ...] name_of_class A string name for the class, with the prior suffix removed. new Returns a copy of this prior with a new id assigned making it distinct next_id project random A random value sampled from this prior replacing_for_path Create a new model replacing the value for a given path with a new value unit_value_for Compute the unit value between 0 and 1 for the physical value. value_for Return a physical value for a value between 0 and 1 with the transformation described by this prior. with_limits Create a new instance of the same prior class with the passed limits. with_message

Attributes

 component_number factor A callable PDF used as a factor in factor graphs identifier label limits rtype lower_unit_limit The lower limit for this prior in unit vector space ndim How many dimensions does this variable have? parameter_string rtype str upper_unit_limit The upper limit for this prior in unit vector space width
value_for(unit, ignore_prior_limits=False)[source]#

Return a physical value for a value between 0 and 1 with the transformation described by this prior.

Parameters

unit (float) – A unit value between 0 and 1.

Return type

A physical value, mapped from the unit value accoridng to the prior.