Note
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Date tick labels#
Matplotlib date plotting is done by converting date instances into
days since an epoch (by default 1970-01-01T00:00:00). The
matplotlib.dates
module provides the converter functions date2num
and num2date
that convert datetime.datetime
and numpy.datetime64
objects to and from Matplotlib's internal representation. These data
types are registered with the unit conversion mechanism described in
matplotlib.units
, so the conversion happens automatically for the user.
The registration process also sets the default tick locator
and
formatter
for the axis to be AutoDateLocator
and
AutoDateFormatter
.
An alternative formatter is the ConciseDateFormatter
,
used in the second Axes
below (see
Formatting date ticks using ConciseDateFormatter), which often removes the need to
rotate the tick labels. The last Axes
formats the dates manually, using
DateFormatter
to format the dates using the format strings documented
at datetime.date.strftime
.
![DefaultFormatter, ConciseFormatter, Manual DateFormatter](../../_images/sphx_glr_date_001.png)
import matplotlib.pyplot as plt
import matplotlib.dates as mdates
import matplotlib.cbook as cbook
# Load a numpy structured array from yahoo csv data with fields date, open,
# close, volume, adj_close from the mpl-data/example directory. This array
# stores the date as an np.datetime64 with a day unit ('D') in the 'date'
# column.
data = cbook.get_sample_data('goog.npz', np_load=True)['price_data']
fig, axs = plt.subplots(3, 1, figsize=(6.4, 7), constrained_layout=True)
# common to all three:
for ax in axs:
ax.plot('date', 'adj_close', data=data)
# Major ticks every half year, minor ticks every month,
ax.xaxis.set_major_locator(mdates.MonthLocator(bymonth=(1, 7)))
ax.xaxis.set_minor_locator(mdates.MonthLocator())
ax.grid(True)
ax.set_ylabel(r'Price [\$]')
# different formats:
ax = axs[0]
ax.set_title('DefaultFormatter', loc='left', y=0.85, x=0.02, fontsize='medium')
ax = axs[1]
ax.set_title('ConciseFormatter', loc='left', y=0.85, x=0.02, fontsize='medium')
ax.xaxis.set_major_formatter(
mdates.ConciseDateFormatter(ax.xaxis.get_major_locator()))
ax = axs[2]
ax.set_title('Manual DateFormatter', loc='left', y=0.85, x=0.02,
fontsize='medium')
# Text in the x axis will be displayed in 'YYYY-mm' format.
ax.xaxis.set_major_formatter(mdates.DateFormatter('%Y-%b'))
# Rotates and right-aligns the x labels so they don't crowd each other.
for label in ax.get_xticklabels(which='major'):
label.set(rotation=30, horizontalalignment='right')
plt.show()
Total running time of the script: ( 0 minutes 1.435 seconds)
Keywords: matplotlib code example, codex, python plot, pyplot Gallery generated by Sphinx-Gallery