Source code for biogeme.expressions.random_variable

"""Arithmetic expressions accepted by Biogeme: random variable for numerical integration

Michel Bierlaire
Fri Jun 27 2025, 14:50:37
"""

from __future__ import annotations

import logging

import jax.numpy as jnp

from biogeme.exceptions import BiogemeError
from .elementary_expressions import Elementary
from .elementary_types import TypeOfElementaryExpression
from .jax_utils import JaxFunctionType

logger = logging.getLogger(__name__)


[docs] class RandomVariable(Elementary): """ Random variable for numerical integration """ expression_type = TypeOfElementaryExpression.RANDOM_VARIABLE def __init__(self, name: str): """Constructor :param name: name of the random variable involved in the integration. :type name: string. """ super().__init__(name) # Index of the random variable
[docs] def deep_flat_copy(self) -> RandomVariable: """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(self)(name=self.name)
@property def safe_rv_id(self) -> int: """Check the presence of the ID before using it""" if self.specific_id is None: raise BiogemeError(f"No id defined for random variable {self.name}") return self.specific_id
[docs] def recursive_construct_jax_function( self, numerically_safe: bool ) -> JaxFunctionType: """ Generates a function to be used by biogeme_jax. Must be overloaded by each expression :return: the function takes two parameters: the parameters, and one row of the database. """ def the_jax_function( parameters: jnp.ndarray, one_row: jnp.ndarray, the_draws: jnp.ndarray, the_random_variables: jnp.ndarray, ) -> jnp.array: return jnp.take(the_random_variables, self.safe_rv_id, axis=-1) return the_jax_function