Matplotlib.dates.ConciseDateFormatter class in Python

Matplotlib is an amazing visualization library in Python for 2D plots of arrays. Matplotlib is a multi-platform data visualization library built on NumPy arrays and designed to work with the broader SciPy stack.

matplotlib.dates.ConciseDateFormatter

The matplotlib.dates.ConciseDateFormatter class is used to figure out the best format to use for the date and also makes it as compact as possible but complete. This is more often used with AutoDateLocator.

Syntax: class matplotlib.dates.ConciseDateFormatter(locator, tz=None, formats=None, offset_formats=None, zero_formats=None, show_offset=True)

Parameters:

locator: This parameter represents the locator that this axis uses.

tz: It is an optional parameter that accepts a string that is passed to dates.date2num.

formats: It is an optional list of 6 strings. It is used to format strings for 6 levels of tick labelling as years, months, days, hours, minutes and seconds. These strings has format codes same as that of strftime. Its defaults are as [ ‘%Y’, ‘%b’, ‘%d’, ‘%H:%M’, ‘%H:%M’, ‘%S.%f’]

zero_formats: It is an optional list of 6 strings. It is used for formatting strings for tick labels that are “zero” for any given tick level. For example, if most ticks are months, ticks around 1 February 2020 will get labeled “Jan” 2020 “March”.Its defaults are as [”, ‘%Y’, ‘%b’, ‘%b-%d’, ‘%H:%M’, ‘%H:%M’].

offset_formats: It is an optional list of 6 strings.It is used for formatting strings for 6 levels that is applied to the “offset” string on the right side of x-axis or top of y-axis. This should completely specify date when combined with the tick labels. The defaults are as [”, ‘%Y’, ‘%Y-%b’, ‘%Y-%b-%d’, ‘%Y-%b-%d’, ‘%Y-%b-%d %H:%M’].

show_offset: It accepts a boolean value and decides whether to show offset or not. By default it is set to True.

Example 1:

import numpy as np
import matplotlib.dates as mdates
import matplotlib.pyplot as plt


# dummy date
dummy_date = np.arange("2020-04-10",
                       "2020-05-14",
                       dtype ="datetime64")

random_x = np.random.rand(len(dummy_date))

figure, axes = plt.subplots()

axes.plot(dummy_date, random_x)
axes.xaxis.set(
    major_locator = mdates.AutoDateLocator(minticks = 1,
                                           maxticks = 5),
)

locator = mdates.AutoDateLocator(minticks = 15,
                                 maxticks = 20)
formatter = mdates.ConciseDateFormatter(locator)

axes.xaxis.set_major_locator(locator)
axes.xaxis.set_major_formatter(formatter)

plt.show()

Output:

Example 2:

import datetime
import matplotlib.pyplot as plt
import matplotlib.dates as mdates
import numpy as np


dummy_date = datetime.datetime(2020, 2, 1)

# random date generator
dates = np.array([dummy_date + datetime.timedelta(hours =(2 * i))
                  for i in range(732)])
date_length = len(dates)

np.random.seed(194567801)
y_axis = np.cumsum(np.random.randn(date_length))

lims = [(np.datetime64('2020-02'),
         np.datetime64('2020-04')),
        (np.datetime64('2020-02-03'),
         np.datetime64('2020-02-15')),
        (np.datetime64('2020-02-03 11:00'),
         np.datetime64('2020-02-04 13:20'))]

figure, axes = plt.subplots(3, 1,
                            constrained_layout = True,
                            figsize =(6, 6))

for nn, ax in enumerate(axes):

    locator = mdates.AutoDateLocator(minticks = 3, maxticks = 7)
    formatter = mdates.ConciseDateFormatter(locator)

    ax.xaxis.set_major_locator(locator)
    ax.xaxis.set_major_formatter(formatter)

    ax.plot(dates, y_axis)
    ax.set_xlim(lims[nn])

axes[0].set_title('Concise Date Formatter')

plt.show()

Output: