.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "11_demos\python_packages\numpy\demo_NpFFT_PyFFTW.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

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

        :ref:`Go to the end <sphx_glr_download_11_demos_python_packages_numpy_demo_NpFFT_PyFFTW.py>`
        to download the full example code.

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

.. _sphx_glr_11_demos_python_packages_numpy_demo_NpFFT_PyFFTW.py:

Numpy FFT, PyFFTW
====================

This example shows how to use the FFT or IFFT from ``Numpy``.
If possible the package PyFFTW is searched. If it is available,
the fast implementation of FFT and IFFT is used from this package (GPL license!!!).

In order to have the fast version of the fourier transform
in ``pyfftw``, align your input data using ``getAlignNdArray``. This is
an idle operation if PyFFTW is not available. Either ``np.fft.fft2``
or ``pyfftw.interfaces.numpy_fft.fft2`` are mapped to ``myfft2``, such the
overall call can be done by using ``myfft2(...)``. The same holds for ``myifft2(...)``.

.. GENERATED FROM PYTHON SOURCE LINES 13-19

.. code-block:: Python


    import numpy as np

    myfft2 = np.fft.fft2  # default: fft2 from numpy
    myifft2 = np.fft.ifft2  # default: ifft2 from numpy








.. GENERATED FROM PYTHON SOURCE LINES 21-22

Define function and overwrite it when ``pyfftw`` is available.

.. GENERATED FROM PYTHON SOURCE LINES 22-47

.. code-block:: Python



    def getAlignNdArray(image):
        return np.array(image)


    try:
        import pyfftw

        myfft2 = pyfftw.interfaces.numpy_fft.fft2  # if PyFFTW: use fft2 from this package
        myifft2 = pyfftw.interfaces.numpy_fft.ifft2
        alignSize = pyfftw.simd_alignment

        def getAlignNdArray(image):
            return pyfftw.n_byte_align(np.array(image), alignSize)

    except ModuleNotFoundError:
        print("pyfftw could not be found. Numpy fft is used instead")


    image = np.random.randn(1024, 512)
    I = getAlignNdArray(image)
    I1 = myfft2(I)
    I2 = myifft2(I)
    I2




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

 .. code-block:: none

    pyfftw could not be found. Numpy fft is used instead

    array([[-4.41454107e-04+0.00000000e+00j, -2.51629340e-04-6.22621070e-04j,
            -5.24166091e-04-8.69670371e-04j, ...,
            -9.68750785e-04-1.40335374e-03j, -5.24166091e-04+8.69670371e-04j,
            -2.51629340e-04+6.22621070e-04j],
           [-1.37564520e-03-5.02280564e-04j, -3.16131226e-04-3.83928675e-04j,
            -2.64524355e-03+1.21308171e-03j, ...,
             6.43585986e-04+4.19576266e-04j, -5.99395508e-04+3.66520961e-04j,
             6.92728343e-04+4.41714402e-04j],
           [-1.00728360e-03+6.71349255e-04j, -2.00100703e-03-3.09363704e-04j,
            -8.92034028e-04-9.69901790e-05j, ...,
             8.30072838e-05+8.28516470e-04j, -3.14040628e-04-9.99640259e-04j,
             3.96885141e-04+1.28553377e-04j],
           ...,
           [-1.39918521e-03+1.49365727e-03j,  1.28884982e-03-2.33037098e-04j,
             7.99750333e-04+1.03343398e-03j, ...,
             1.55898393e-03+2.42627676e-03j, -4.51848616e-04+3.83616458e-04j,
             4.70787993e-04-9.90595756e-05j],
           [-1.00728360e-03-6.71349255e-04j,  3.96885141e-04-1.28553377e-04j,
            -3.14040628e-04+9.99640259e-04j, ...,
             3.99798804e-04-6.90250285e-04j, -8.92034028e-04+9.69901790e-05j,
            -2.00100703e-03+3.09363704e-04j],
           [-1.37564520e-03+5.02280564e-04j,  6.92728343e-04-4.41714402e-04j,
            -5.99395508e-04-3.66520961e-04j, ...,
            -8.33580524e-05+1.38016544e-03j, -2.64524355e-03-1.21308171e-03j,
            -3.16131226e-04+3.83928675e-04j]])




.. rst-class:: sphx-glr-timing

   **Total running time of the script:** (0 minutes 0.032 seconds)


.. _sphx_glr_download_11_demos_python_packages_numpy_demo_NpFFT_PyFFTW.py:

.. only:: html

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

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

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

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

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

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

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