"""
===============
Tick formatters
===============

Show the different tick formatters.
"""

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


# Setup a plot such that only the bottom spine is shown
def setup(ax):
    ax.spines['right'].set_color('none')
    ax.spines['left'].set_color('none')
    ax.yaxis.set_major_locator(ticker.NullLocator())
    ax.spines['top'].set_color('none')
    ax.xaxis.set_ticks_position('bottom')
    ax.tick_params(which='major', width=1.00, length=5)
    ax.tick_params(which='minor', width=0.75, length=2.5, labelsize=10)
    ax.set_xlim(0, 5)
    ax.set_ylim(0, 1)
    ax.patch.set_alpha(0.0)


plt.figure(figsize=(8, 5))
n = 6

# Null formatter
ax = plt.subplot(n, 1, 1)
setup(ax)
ax.xaxis.set_major_locator(ticker.MultipleLocator(1.00))
ax.xaxis.set_minor_locator(ticker.MultipleLocator(0.25))
ax.xaxis.set_major_formatter(ticker.NullFormatter())
ax.xaxis.set_minor_formatter(ticker.NullFormatter())
ax.text(0.0, 0.1, "NullFormatter()", fontsize=16, transform=ax.transAxes)

# Fixed formatter
ax = plt.subplot(n, 1, 2)
setup(ax)
ax.xaxis.set_major_locator(ticker.MultipleLocator(1.0))
ax.xaxis.set_minor_locator(ticker.MultipleLocator(0.25))
majors = ["", "0", "1", "2", "3", "4", "5"]
ax.xaxis.set_major_formatter(ticker.FixedFormatter(majors))
minors = [""] + ["%.2f" % (x-int(x)) if (x-int(x))
                 else "" for x in np.arange(0, 5, 0.25)]
ax.xaxis.set_minor_formatter(ticker.FixedFormatter(minors))
ax.text(0.0, 0.1, "FixedFormatter(['', '0', '1', ...])",
        fontsize=15, transform=ax.transAxes)


# Func formatter
def major_formatter(x, pos):
    return "[%.2f]" % x


ax = plt.subplot(n, 1, 3)
setup(ax)
ax.xaxis.set_major_locator(ticker.MultipleLocator(1.00))
ax.xaxis.set_minor_locator(ticker.MultipleLocator(0.25))
ax.xaxis.set_major_formatter(ticker.FuncFormatter(major_formatter))
ax.text(0.0, 0.1, 'FuncFormatter(lambda x, pos: "[%.2f]" % x)',
        fontsize=15, transform=ax.transAxes)


# FormatStr formatter
ax = plt.subplot(n, 1, 4)
setup(ax)
ax.xaxis.set_major_locator(ticker.MultipleLocator(1.00))
ax.xaxis.set_minor_locator(ticker.MultipleLocator(0.25))
ax.xaxis.set_major_formatter(ticker.FormatStrFormatter(">%d<"))
ax.text(0.0, 0.1, "FormatStrFormatter('>%d<')",
        fontsize=15, transform=ax.transAxes)

# Scalar formatter
ax = plt.subplot(n, 1, 5)
setup(ax)
ax.xaxis.set_major_locator(ticker.AutoLocator())
ax.xaxis.set_minor_locator(ticker.AutoMinorLocator())
ax.xaxis.set_major_formatter(ticker.ScalarFormatter(useMathText=True))
ax.text(0.0, 0.1, "ScalarFormatter()", fontsize=15, transform=ax.transAxes)

# StrMethod formatter
ax = plt.subplot(n, 1, 6)
setup(ax)
ax.xaxis.set_major_locator(ticker.MultipleLocator(1.00))
ax.xaxis.set_minor_locator(ticker.MultipleLocator(0.25))
ax.xaxis.set_major_formatter(ticker.StrMethodFormatter("{x}"))
ax.text(0.0, 0.1, "StrMethodFormatter('{x}')",
        fontsize=15, transform=ax.transAxes)

# Push the top of the top axes outside the figure because we only show the
# bottom spine.
plt.subplots_adjust(left=0.05, right=0.95, bottom=0.05, top=1.05)

plt.show() 

　

M:\______\tick-formatters.py:46: UserWarning: 
  FixedFormatter should only be used together with FixedLocator
  ax.xaxis.set_major_formatter(ticker.FixedFormatter(majors))
M:\______\tick-formatters.py:49: UserWarning: 
  FixedFormatter should only be used together with FixedLocator
  ax.xaxis.set_minor_formatter(ticker.FixedFormatter(minors)) 

E:\______\tick-formatters.py:46: UserWarning: 
  FixedFormatter should only be used together with FixedLocator
  ax.xaxis.set_major_formatter(ticker.FixedFormatter(majors))
E:\______\tick-formatters.py:49: UserWarning: 
  FixedFormatter should only be used together with FixedLocator
  ax.xaxis.set_minor_formatter(ticker.FixedFormatter(minors)) 

"""
===============
Tick formatters
===============

Tick formatters define how the numeric value associated with a tick on an axis
is formatted as a string.

This example illustrates the usage and effect of the most common formatters.

The tick format is configured via the function `~.Axis.set_major_formatter`
or `~.Axis.set_minor_formatter`. It accepts:

- a format string, which implicitly creates a `.StrMethodFormatter`.
- a function,  implicitly creates a `.FuncFormatter`.
- an instance of a `.Formatter` subclass. The most common are

  - `.NullFormatter`: No labels on the ticks.
  - `.StrMethodFormatter`: Use string `str.format` method.
  - `.FormatStrFormatter`: Use %-style formatting.
  - `.FuncFormatter`: Define labels through a function.
  - `.FixedFormatter`: Set the label strings explicitly.
  - `.ScalarFormatter`: Default formatter for scalars: auto-pick the format string.
  - `.PercentFormatter`: Format labels as a percentage.

  See :ref:`formatters` for a complete list.

"""

import matplotlib.pyplot as plt

from matplotlib import ticker


def setup(ax, title):
    """Set up common parameters for the Axes in the example."""
    # only show the bottom spine
    ax.yaxis.set_major_locator(ticker.NullLocator())
    ax.spines[['left', 'right', 'top']].set_visible(False)

    # define tick positions
    ax.xaxis.set_major_locator(ticker.MultipleLocator(1.00))
    ax.xaxis.set_minor_locator(ticker.MultipleLocator(0.25))

    ax.xaxis.set_ticks_position('bottom')
    ax.tick_params(which='major', width=1.00, length=5)
    ax.tick_params(which='minor', width=0.75, length=2.5, labelsize=10)
    ax.set_xlim(0, 5)
    ax.set_ylim(0, 1)
    ax.text(0.0, 0.2, title, transform=ax.transAxes,
            fontsize=14, fontname='Monospace', color='tab:blue')


fig = plt.figure(figsize=(8, 8), layout='constrained')
fig0, fig1, fig2 = fig.subfigures(3, height_ratios=[1.5, 1.5, 7.5])

fig0.suptitle('String Formatting', fontsize=16, x=0, ha='left')
ax0 = fig0.subplots()

setup(ax0, title="'{x} km'")
ax0.xaxis.set_major_formatter('{x} km')


fig1.suptitle('Function Formatting', fontsize=16, x=0, ha='left')
ax1 = fig1.subplots()

setup(ax1, title="def(x, pos): return str(x-5)")
ax1.xaxis.set_major_formatter(lambda x, pos: str(x-5))


fig2.suptitle('Formatter Object Formatting', fontsize=16, x=0, ha='left')
axs2 = fig2.subplots(7, 1)

setup(axs2[0], title="NullFormatter()")
axs2[0].xaxis.set_major_formatter(ticker.NullFormatter())

setup(axs2[1], title="StrMethodFormatter('{x:.3f}')")
axs2[1].xaxis.set_major_formatter(ticker.StrMethodFormatter("{x:.3f}"))

setup(axs2[2], title="FormatStrFormatter('#%d')")
axs2[2].xaxis.set_major_formatter(ticker.FormatStrFormatter("#%d"))


def fmt_two_digits(x, pos):
    return f'[{x:.2f}]'


setup(axs2[3], title='FuncFormatter("[{:.2f}]".format)')
axs2[3].xaxis.set_major_formatter(ticker.FuncFormatter(fmt_two_digits))

setup(axs2[4], title="FixedFormatter(['A', 'B', 'C', 'D', 'E', 'F'])")
# FixedFormatter should only be used together with FixedLocator.
# Otherwise, one cannot be sure where the labels will end up.
positions = [0, 1, 2, 3, 4, 5]
labels = ['A', 'B', 'C', 'D', 'E', 'F']
axs2[4].xaxis.set_major_locator(ticker.FixedLocator(positions))
axs2[4].xaxis.set_major_formatter(ticker.FixedFormatter(labels))

setup(axs2[5], title="ScalarFormatter()")
axs2[5].xaxis.set_major_formatter(ticker.ScalarFormatter(useMathText=True))

setup(axs2[6], title="PercentFormatter(xmax=5)")
axs2[6].xaxis.set_major_formatter(ticker.PercentFormatter(xmax=5))

plt.show() 

　Python 3.11.6 (matplotlib 3.7.1) 及び Python 3.12.0 (matplotlib 3.8.1) 共に、正常実行です。

　

• 2023/12/11 Ver=1.04 Python 3.12.0 (matplotlib 3.8.1)で確認
• 2023/12/11 Ver=1.04 Python 3.11.6 (matplotlib 3.7.1)で確認
• 2023/04/06 Ver=1.03 Python 3.11.2 で確認
• 2020/11/03 Ver=1.01 Python 3.7.8 で確認
• 2018/12/07 Ver=1.01 初版リリース

Top