Matplotlib.dates.DateFormatter 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.DateFormatter

The matplotlib.dates.DateFormatter class is used to format a tick (in seconds since the epoch) with a string of strftime format. Its base class is matplotlib.ticker.Formatter.

Syntax: class matplotlib.dates.DateFormatter(fmt, tz=None)

Parameters:

1. fmt: It accepts a strftime format string for formatting and is a required argument.
2. tz: It holds information regarding the timezone. If set to none it ignores the timezone information while formatting of the date string.

Example 1:

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


total_bars = 25
numpy.random.seed(total_bars)

dates = pandas.date_range('3/4/2020',
                          periods=total_bars,
                          freq='m')

diff = pandas.DataFrame(
    data=numpy.random.randn(total_bars),
    index=dates,
    columns=['A']
)

figure, axes = plt.subplots(figsize=(10, 6))

axes.xaxis.set_major_formatter(mdates.DateFormatter('%Y-%m'))

axes.bar(diff.index,
         diff['A'],
         width=25,
         align='center')

Output:

Example 2:

import matplotlib
import matplotlib.pyplot as plt
from datetime import datetime

origin = ['2020-02-05 17:17:55',
          '2020-02-05 17:17:51',
          '2020-02-05 17:17:49']

a = [datetime.strptime(d, '%Y-%m-%d %H:%M:%S') for d in origin]

b = ['35.764299', '20.3008', '36.94704']

x = matplotlib.dates.date2num(a)
formatter = matplotlib.dates.DateFormatter('%H:%M:%S')

figure = plt.figure()
axes = figure.add_subplot(1, 1, 1)

axes.xaxis.set_major_formatter(formatter)
plt.setp(axes.get_xticklabels(), rotation = 15)

axes.plot(x, b)
plt.show()

Output: