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

    Click :ref:`here <sphx_glr_download_auto_examples_plot_backend.py>` to download the full example code
.. rst-class:: sphx-glr-example-title

.. _sphx_glr_auto_examples_plot_backend.py:



.. _l-example-backend-api:

ONNX Runtime Backend for ONNX
=============================

*ONNX Runtime* extends the 
`onnx backend API <https://github.com/onnx/onnx/blob/master/docs/ImplementingAnOnnxBackend.md>`_
to run predictions using this runtime.
Let's use the API to compute the prediction
of a simple logistic regression model.



.. code-block:: python

    import numpy as np
    from onnxruntime import datasets
    from onnxruntime.capi.onnxruntime_pybind11_state import InvalidArgument
    import onnxruntime.backend as backend
    from onnx import load

    name = datasets.get_example("logreg_iris.onnx")
    model = load(name)

    rep = backend.prepare(model, 'CPU')
    x = np.array([[-1.0, -2.0]], dtype=np.float32)
    try:
        label, proba = rep.run(x)
        print("label={}".format(label))
        print("probabilities={}".format(proba))
    except (RuntimeError, InvalidArgument) as e:
        print(e)





.. rst-class:: sphx-glr-script-out

 Out:

 .. code-block:: none

    [ONNXRuntimeError] : 2 : INVALID_ARGUMENT : Got invalid dimensions for input: float_input for the following indices
     index: 0 Got: 1 Expected: 3
     Please fix either the inputs or the model.


The device depends on how the package was compiled,
GPU or CPU.



.. code-block:: python

    from onnxruntime import get_device
    print(get_device())





.. rst-class:: sphx-glr-script-out

 Out:

 .. code-block:: none

    CPU


The backend can also directly load the model
without using *onnx*.



.. code-block:: python


    rep = backend.prepare(name, 'CPU')
    x = np.array([[-1.0, -2.0]], dtype=np.float32)
    try:
        label, proba = rep.run(x)
        print("label={}".format(label))
        print("probabilities={}".format(proba))
    except (RuntimeError, InvalidArgument) as e:
        print(e)





.. rst-class:: sphx-glr-script-out

 Out:

 .. code-block:: none

    [ONNXRuntimeError] : 2 : INVALID_ARGUMENT : Got invalid dimensions for input: float_input for the following indices
     index: 0 Got: 1 Expected: 3
     Please fix either the inputs or the model.


The backend API is implemented by other frameworks
and makes it easier to switch between multiple runtimes
with the same API.


**Total running time of the script:** ( 0 minutes  0.025 seconds)


.. _sphx_glr_download_auto_examples_plot_backend.py:


.. only :: html

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



  .. container:: sphx-glr-download

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



  .. container:: sphx-glr-download

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


.. only:: html

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

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