biogeme.expressions.logit_expressions module

Arithmetic expressions accepted by Biogeme: logit

author:

Michel Bierlaire

date:

Sat Sep 9 15:28:39 2023

class biogeme.expressions.logit_expressions.LogLogit(util, av, choice)

Bases: Expression

Expression capturing the logit formula.

It contains one formula for the target alternative, a dict of formula for the availabilities and a dict of formulas for the utilities

Parameters:

• util (dict[int, ExpressionOrNumeric])

• av (dict[int, ExpressionOrNumeric] | None)

• choice (ExpressionOrNumeric)

av: dict[int, Expression] | None

dict of availability formulas

choice: Expression

expression for the chosen alternative

deep_flat_copy()

Provides a copy of the expression. It is deep in the sense that it generates copies of the children. It is flat in the sense that any MultipleExpression is transformed into the currently selected expression. The flat part is irrelevant for this expression.

Return type:

LogLogit

getValue()

Warning

This function is deprecated. Use get_value() instead.

Return type:

float

get_value()

Evaluates the value of the expression

Returns:

value of the expression

Return type:

float

Raises:

• BiogemeError – if the chosen alternative does not correspond to any of the utility functions

• BiogemeError – if the chosen alternative does not correspond to any of entry in the availability condition

logit_choice_avail()

Extract a dict with all elementary expressions of a specific type

Returns:

returns a dict with the variables appearing in the expression the keys being their names.

Return type:

dict(string:biogeme.expressions.Expression)

recursive_construct_jax_function(numerically_safe)

Generates a JAX-compatible function. This function computes the logit-based probability calculation based on availability and utility values.

Return type:

Callable[[Array, Array, Array, Array], array]

Returns:

A function that takes parameters, a row of the database, and random draws.

Parameters:

numerically_safe (bool)

biogeme.expressions.logit_expressions.index_of(key, keys)

Function returning the index of a kex for biogeme_jax

Parameters:

• key (float)

• keys (list[int])