.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "auto_examples/sampling/_plot_b02nested.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        :ref:`Go to the end <sphx_glr_download_auto_examples_sampling__plot_b02nested.py>`
        to download the full example code.

.. rst-class:: sphx-glr-example-title

.. _sphx_glr_auto_examples_sampling__plot_b02nested.py:


Nested logit
============

Estimation of a nested logit model using sampling of alternatives.

Michel Bierlaire
Sat Jul 26 2025, 13:01:22

.. GENERATED FROM PYTHON SOURCE LINES 11-34

.. code-block:: Python


    import pandas as pd
    from alternatives import ID_COLUMN, all_alternatives, alternatives, asian, partitions
    from compare import compare
    from IPython.core.display_functions import display
    from specification_sampling import V, combined_variables

    import biogeme.biogeme_logging as blog
    from biogeme.biogeme import BIOGEME
    from biogeme.expressions import Beta
    from biogeme.nests import NestsForNestedLogit, OneNestForNestedLogit
    from biogeme.results_processing import (
        EstimationResults,
        get_pandas_estimated_parameters,
    )
    from biogeme.sampling_of_alternatives import (
        ChoiceSetsGeneration,
        GenerateModel,
        SamplingContext,
        generate_segment_size,
    )
    from biogeme.tools import timeit


.. GENERATED FROM PYTHON SOURCE LINES 35-37

.. code-block:: Python

    logger = blog.get_screen_logger(level=blog.INFO)


.. GENERATED FROM PYTHON SOURCE LINES 38-46

.. code-block:: Python

    SAMPLE_SIZE = 20  # out of 100
    SAMPLE_SIZE_MEV = 33  # out of 33
    CHOICE_COLUMN = 'nested_0'
    PARTITION = 'downtown'
    MEV_PARTITION = 'uniform_asian'
    MODEL_NAME = f'nested_{PARTITION}_{SAMPLE_SIZE}'
    FILE_NAME = f'{MODEL_NAME}.dat'


.. GENERATED FROM PYTHON SOURCE LINES 47-51

.. code-block:: Python

    the_partition = partitions.get(PARTITION)
    if the_partition is None:
        raise ValueError(f'Unknown partition: {PARTITION}')


.. GENERATED FROM PYTHON SOURCE LINES 52-54

.. code-block:: Python

    segment_sizes = generate_segment_size(SAMPLE_SIZE, the_partition.number_of_segments())


.. GENERATED FROM PYTHON SOURCE LINES 55-56

We use all alternatives in the nest.

.. GENERATED FROM PYTHON SOURCE LINES 56-61

.. code-block:: Python

    mev_partition = partitions.get(MEV_PARTITION)
    if mev_partition is None:
        raise ValueError(f'Unknown partition: {MEV_PARTITION}')
    mev_segment_sizes = [SAMPLE_SIZE_MEV]


.. GENERATED FROM PYTHON SOURCE LINES 62-64

.. code-block:: Python

    observations = pd.read_csv('obs_choice.dat')


.. GENERATED FROM PYTHON SOURCE LINES 65-79

.. code-block:: Python

    context = SamplingContext(
        the_partition=the_partition,
        sample_sizes=segment_sizes,
        individuals=observations,
        choice_column=CHOICE_COLUMN,
        alternatives=alternatives,
        id_column=ID_COLUMN,
        biogeme_file_name=FILE_NAME,
        utility_function=V,
        combined_variables=combined_variables,
        mev_partition=mev_partition,
        mev_sample_sizes=mev_segment_sizes,
    )


.. GENERATED FROM PYTHON SOURCE LINES 80-82

.. code-block:: Python

    logger.info(context.reporting())


.. GENERATED FROM PYTHON SOURCE LINES 83-86

.. code-block:: Python

    the_data_generation = ChoiceSetsGeneration(context=context)
    the_model_generation = GenerateModel(context=context)


.. GENERATED FROM PYTHON SOURCE LINES 87-89

.. code-block:: Python

    biogeme_database = the_data_generation.sample_and_merge(recycle=False)


.. GENERATED FROM PYTHON SOURCE LINES 90-91

Definition of the nest.

.. GENERATED FROM PYTHON SOURCE LINES 91-100

.. code-block:: Python

    mu_asian = Beta('mu_asian', 1.0, 1.0, None, 0)
    nest_asian = OneNestForNestedLogit(
        nest_param=mu_asian, list_of_alternatives=asian, name='asian'
    )
    nests = NestsForNestedLogit(
        choice_set=all_alternatives,
        tuple_of_nests=(nest_asian,),
    )


.. GENERATED FROM PYTHON SOURCE LINES 101-103

.. code-block:: Python

    log_probability = the_model_generation.get_nested_logit(nests)


.. GENERATED FROM PYTHON SOURCE LINES 104-107

.. code-block:: Python

    the_biogeme = BIOGEME(biogeme_database, log_probability)
    the_biogeme.model_name = MODEL_NAME


.. GENERATED FROM PYTHON SOURCE LINES 108-109

Calculate the null log likelihood for reporting.

.. GENERATED FROM PYTHON SOURCE LINES 109-113

.. code-block:: Python

    the_biogeme.calculate_null_loglikelihood(
        {i: 1 for i in range(context.total_sample_size)}
    )


.. GENERATED FROM PYTHON SOURCE LINES 114-115

Estimate the parameters.

.. GENERATED FROM PYTHON SOURCE LINES 115-123

.. code-block:: Python

    try:
        results = EstimationResults.from_yaml_file(
            filename=f'saved_results/{the_biogeme.model_name}.yaml'
        )
    except FileNotFoundError:
        with timeit(f'Estimate of model {the_biogeme.model_name}'):
            results = the_biogeme.estimate()


.. GENERATED FROM PYTHON SOURCE LINES 124-126

.. code-block:: Python

    print(results.short_summary())


.. GENERATED FROM PYTHON SOURCE LINES 127-131

.. code-block:: Python

    parameters_tables = get_pandas_estimated_parameters(estimation_results=results)
    estimated_parameters = parameters_tables['Estimated parameters']
    display(estimated_parameters)


.. GENERATED FROM PYTHON SOURCE LINES 132-134

.. code-block:: Python

    df, msg = compare(estimated_parameters)


.. GENERATED FROM PYTHON SOURCE LINES 135-137

.. code-block:: Python

    print(df)


.. GENERATED FROM PYTHON SOURCE LINES 138-139

.. code-block:: Python

    print(msg)


.. _sphx_glr_download_auto_examples_sampling__plot_b02nested.py:

.. only:: html

  .. container:: sphx-glr-footer sphx-glr-footer-example

    .. container:: sphx-glr-download sphx-glr-download-jupyter

      :download:`Download Jupyter notebook: _plot_b02nested.ipynb <_plot_b02nested.ipynb>`

    .. container:: sphx-glr-download sphx-glr-download-python

      :download:`Download Python source code: _plot_b02nested.py <_plot_b02nested.py>`

    .. container:: sphx-glr-download sphx-glr-download-zip

      :download:`Download zipped: _plot_b02nested.zip <_plot_b02nested.zip>`


.. only:: html

 .. rst-class:: sphx-glr-signature

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_