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

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

.. _sphx_glr_gallery_text_labels_and_annotations_date_index_formatter.py:


=====================================
Custom tick formatter for time series
=====================================

When plotting time series, e.g., financial time series, one often wants
to leave out days on which there is no data, i.e. weekends.  The example
below shows how to use an 'index formatter' to achieve the desired plot




.. image:: /gallery/text_labels_and_annotations/images/sphx_glr_date_index_formatter_001.png
    :class: sphx-glr-single-img





.. code-block:: python

    import numpy as np
    import matplotlib.pyplot as plt
    import matplotlib.cbook as cbook
    import matplotlib.ticker as ticker

    # Load a numpy record array from yahoo csv data with fields date, open, close,
    # volume, adj_close from the mpl-data/example directory. The record array
    # stores the date as an np.datetime64 with a day unit ('D') in the date column.
    with cbook.get_sample_data('goog.npz') as datafile:
        r = np.load(datafile)['price_data'].view(np.recarray)
    r = r[-30:]  # get the last 30 days
    # Matplotlib works better with datetime.datetime than np.datetime64, but the
    # latter is more portable.
    date = r.date.astype('O')

    # first we'll do it the default way, with gaps on weekends
    fig, axes = plt.subplots(ncols=2, figsize=(8, 4))
    ax = axes[0]
    ax.plot(date, r.adj_close, 'o-')
    ax.set_title("Default")
    fig.autofmt_xdate()

    # next we'll write a custom formatter
    N = len(r)
    ind = np.arange(N)  # the evenly spaced plot indices


    def format_date(x, pos=None):
        thisind = np.clip(int(x + 0.5), 0, N - 1)
        return date[thisind].strftime('%Y-%m-%d')

    ax = axes[1]
    ax.plot(ind, r.adj_close, 'o-')
    ax.xaxis.set_major_formatter(ticker.FuncFormatter(format_date))
    ax.set_title("Custom tick formatter")
    fig.autofmt_xdate()

    plt.show()


.. _sphx_glr_download_gallery_text_labels_and_annotations_date_index_formatter.py:


.. only :: html

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



  .. container:: sphx-glr-download

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



  .. container:: sphx-glr-download

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


.. only:: html

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

    Keywords: matplotlib code example, codex, python plot, pyplot
    `Gallery generated by Sphinx-Gallery
    <https://sphinx-gallery.readthedocs.io>`_
