.. note:: :class: sphx-glr-download-link-note Click :ref:`here ` to download the full example code .. rst-class:: sphx-glr-example-title .. _sphx_glr_gallery_recipes_common_date_problems.py: Fixing common date annoyances ============================= Matplotlib allows you to natively plots python datetime instances, and for the most part does a good job picking tick locations and string formats. There are a couple of things it does not handle so gracefully, and here are some tricks to help you work around them. We'll load up some sample date data which contains datetime.date objects in a numpy record array:: In [63]: datafile = cbook.get_sample_data('goog.npz') In [64]: r = np.load(datafile)['price_data'].view(np.recarray) In [65]: r.dtype Out[65]: dtype([('date', '] you will see that the x tick labels are all squashed together. .. code-block:: python import matplotlib.cbook as cbook import matplotlib.dates as mdates import numpy as np import matplotlib.pyplot as plt with cbook.get_sample_data('goog.npz') as datafile: r = np.load(datafile)['price_data'].view(np.recarray) # Matplotlib prefers datetime instead of np.datetime64. date = r.date.astype('O') fig, ax = plt.subplots() ax.plot(date, r.close) ax.set_title('Default date handling can cause overlapping labels') .. image:: /gallery/recipes/images/sphx_glr_common_date_problems_001.png :class: sphx-glr-single-img Another annoyance is that if you hover the mouse over the window and look in the lower right corner of the matplotlib toolbar (:ref:`navigation-toolbar`) at the x and y coordinates, you see that the x locations are formatted the same way the tick labels are, e.g., "Dec 2004". What we'd like is for the location in the toolbar to have a higher degree of precision, e.g., giving us the exact date out mouse is hovering over. To fix the first problem, we can use :func:`matplotlib.figure.Figure.autofmt_xdate` and to fix the second problem we can use the ``ax.fmt_xdata`` attribute which can be set to any function that takes a scalar and returns a string. matplotlib has a number of date formatters built in, so we'll use one of those. .. code-block:: python fig, ax = plt.subplots() ax.plot(date, r.close) # rotate and align the tick labels so they look better fig.autofmt_xdate() # use a more precise date string for the x axis locations in the # toolbar ax.fmt_xdata = mdates.DateFormatter('%Y-%m-%d') ax.set_title('fig.autofmt_xdate fixes the labels') .. image:: /gallery/recipes/images/sphx_glr_common_date_problems_002.png :class: sphx-glr-single-img Now when you hover your mouse over the plotted data, you'll see date format strings like 2004-12-01 in the toolbar. .. code-block:: python plt.show() .. _sphx_glr_download_gallery_recipes_common_date_problems.py: .. only :: html .. container:: sphx-glr-footer :class: sphx-glr-footer-example .. container:: sphx-glr-download :download:`Download Python source code: common_date_problems.py ` .. container:: sphx-glr-download :download:`Download Jupyter notebook: common_date_problems.ipynb ` .. only:: html .. rst-class:: sphx-glr-signature Keywords: matplotlib code example, codex, python plot, pyplot `Gallery generated by Sphinx-Gallery `_