Matplotlib 简明教程

Matplotlib - Anchored Artists

在 Matplotlib 中， Artist 是表示绘图中几乎所有组件的基本对象。无论是线、文本、轴还是任何其他图形元素，Matplotlib 绘图中的所有内容都是 Artist 的实例或从 Artist 类派生而来。

In Matplotlib, an Artist is a fundamental object that represents almost all components of a plot. Whether it’s a line, text, axis, or any other graphical element, everything in a Matplotlib plot is an instance of an Artist or is derived from the Artist class.

Anchored Artists 是自定义 artist 的特殊类型，可以锚定到绘图上的特定位置。它们可用于添加注释、箭头和其他锚定在特定点或区域上的自定义元素。

Anchored Artists are a special type of custom artist that can be anchored to specific positions on a plot. They are useful for adding annotations, arrows, and other custom elements that are anchored to a particular point or region.

请参见下面的参考示例 −

See the below example for refence −

anchored artists intro

在上图中，您可以观察到文本框、圆环和大小栏被固定在绘图上的特定位置。

In the above image, you can observe that text boxes, circles, and size bars are anchored at specific positions on the plot.

Anchored Artists in Matplotlib

在 Matplotlib 中有两个提供固定化对象的模块，分别是 −

There are two modules that provides Anchored Artists in Matplotlib, which are −

  1. Matplotlib.offsetbox

  2. Mpl_toolkits.axes_grid1.anchored_artists

The matplotlib.offsetbox module

此模块提供了 AnchoredOffsetbox 和 AnchoredText 类，允许您相对于父轴或特定锚点固定任意的对象或文本。它们可用于更通用的注释和修饰。

This module provides classes like AnchoredOffsetbox and AnchoredText, allowing you to anchor arbitrary artists or text relative to the parent axes or a specific anchor point. These can be used for more general-purpose annotations and decorations.

现在，我们使用 matplotlib.offsetbox 模块中的 AnchoredText 类在绘图上的特定位置实现两个 anchored text boxes 。

Now, let’s use the AnchoredText class from the matplotlib.offsetbox module to implement two anchored text boxes at specific location on the plot.

import matplotlib.pyplot as plt
from matplotlib.offsetbox import AnchoredText

# Create a figure and axis
fig, ax = plt.subplots(figsize=(7, 4))

# Anchored Text Box 1
at = AnchoredText("Anchored text-box 1",
   loc='upper left', prop=dict(size=10), frameon=True)
at.patch.set_boxstyle("round,pad=0.,rounding_size=0.2")
ax.add_artist(at)

# Anchored Text Box 2
at2 = AnchoredText("Anchored text-box 2",
   loc='center', prop=dict(size=16), frameon=True,
   bbox_to_anchor=(0.5, 0.5),
   bbox_transform=ax.transAxes)
at2.patch.set_boxstyle("round,pad=0.,rounding_size=0.5")
ax.add_artist(at2)

# Display the plot
plt.show()

执行上述代码，我们将得到以下输出 −

On executing the above code we will get the following output −

anchored artists ex1

The mpl_toolkits.axes_grid1.anchored_artists module

此模块提供了 AnchoredDirectionArrows 、 AnchoredAuxTransformBox 、 AnchoredDrawingArea 和 AnchoredSizeBar 等特殊固定化对象。该类的每一个都用于不同的目的。

This module offers specialized Anchored Artists like AnchoredDirectionArrows, AnchoredAuxTransformBox, AnchoredDrawingArea, and AnchoredSizeBar. Eachof this class is used to different porposes.

我们来看每个类的用法 −

Let’s see the usase of the each class −

  1. AnchoredAuxTransformBox − An anchored container with transformed coordinates.

  2. AnchoredDirectionArrows − Draw two perpendicular arrows to indicate directions.

  3. AnchoredDrawingArea − An anchored container with a fixed size and fillable DrawingArea.

  4. AnchoredSizeBar − Draw a horizontal scale bar with a center-aligned label underneath.

本示例演示如何使用 AnchoredDirectionArrows 类将视觉上吸引人的固定化方向箭头添加到 Matplotlib 绘图。

This example demonstrates how to use AnchoredDirectionArrows class to add a visually appealing anchored direction arrow to the Matplotlib plot.

import matplotlib.pyplot as plt
import numpy as np
import matplotlib.font_manager as fm
from mpl_toolkits.axes_grid1.anchored_artists import AnchoredDirectionArrows

np.random.seed(19680801)

fig, ax = plt.subplots(figsize=(7, 4))
ax.imshow(np.random.random((10, 10)))

# Rotated arrow
fontprops = fm.FontProperties(family='serif')

rotated_arrow = AnchoredDirectionArrows(
   ax.transAxes,
   '30', '120',
   loc='center',
   color='w',
   angle=30,
   fontproperties=fontprops
)
ax.add_artist(rotated_arrow)

plt.show()

执行上述代码，我们将得到以下输出 −

On executing the above code we will get the following output −

anchored artists ex2