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

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

.. _sphx_glr_intro_scipy_auto_examples_plot_connect_measurements.py:


=============================
Demo connected components
=============================

Extracting and labeling connected components in a 2D array



.. code-block:: python


    import numpy as np
    from matplotlib import pyplot as plt







Generate some binary data



.. code-block:: python

    np.random.seed(0)
    x, y = np.indices((100, 100))
    sig = np.sin(2*np.pi*x/50.) * np.sin(2*np.pi*y/50.) * (1+x*y/50.**2)**2
    mask = sig > 1

    plt.figure(figsize=(7, 3.5))
    plt.subplot(1, 2, 1)
    plt.imshow(sig)
    plt.axis('off')
    plt.title('sig')

    plt.subplot(1, 2, 2)
    plt.imshow(mask, cmap=plt.cm.gray)
    plt.axis('off')
    plt.title('mask')
    plt.subplots_adjust(wspace=.05, left=.01, bottom=.01, right=.99, top=.9)





.. image:: /intro/scipy/auto_examples/images/sphx_glr_plot_connect_measurements_001.png
    :class: sphx-glr-single-img




Label connected components



.. code-block:: python

    from scipy import ndimage
    labels, nb = ndimage.label(mask)

    plt.figure(figsize=(3.5, 3.5))
    plt.imshow(labels)
    plt.title('label')
    plt.axis('off')

    plt.subplots_adjust(wspace=.05, left=.01, bottom=.01, right=.99, top=.9)





.. image:: /intro/scipy/auto_examples/images/sphx_glr_plot_connect_measurements_002.png
    :class: sphx-glr-single-img




Extract the 4th connected component, and crop the array around it



.. code-block:: python

    sl = ndimage.find_objects(labels==4)
    plt.figure(figsize=(3.5, 3.5))
    plt.imshow(sig[sl[0]])
    plt.title('Cropped connected component')
    plt.axis('off')

    plt.subplots_adjust(wspace=.05, left=.01, bottom=.01, right=.99, top=.9)

    plt.show()





.. image:: /intro/scipy/auto_examples/images/sphx_glr_plot_connect_measurements_003.png
    :class: sphx-glr-single-img




**Total running time of the script:** ( 0 minutes  0.047 seconds)


.. _sphx_glr_download_intro_scipy_auto_examples_plot_connect_measurements.py:


.. only :: html

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



  .. container:: sphx-glr-download

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



  .. container:: sphx-glr-download

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


.. only:: html

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

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