Matplotlib 简明教程

Matplotlib - Grids

总体而言，数据可视化和绘图， grids 指的是绘图区域上的水平和垂直线集合。网格线有助于更好地理解绘图中的数据。通常，这些线与 x 轴和 y 轴上的主要刻度线对齐。它们可以增强绘图的可读性并使其更容易评估值。

In general data visualization and plotting, grids refer to the set of horizontal and vertical lines over the plot area. Gridlines are useful for a better understanding of the data on the plots. Typically, these lines are aligned with the major tick marks on both the x-axis and the y-axis. They can enhance the readability of the plot and make it easier to estimate values.

参阅以下示例图像 −

See the below image for reference −

grids

主要有两种类型的网格线 -

There are two main types of gridlines −

  1. Major Gridlines − These are the primary gridlines that align with the major tick marks on the axes.

  2. Minor Gridlines − These are additional gridlines between the major gridlines and align with the minor tick marks on the axes.

Introduction to Grids in Matplotlib

启用网格线是 Matplotlib 中一个简单的过程。pyplot.grid() 方法将主要网格线添加到绘图中，并提供其他自定义选项，包括调整线型、线宽、颜色和透明度。

Enabling gridlines is a straightforward process in Matplotlib. The pyplot.grid() method adds major gridlines to the plot with additional customization options including adjusting the linestyle, linewidth, color, and transparency.

让我们探索向绘图中添加网格线的不同方法。

Let’s explore different approaches to adding gridlines to plots.

Basic Plot with Grids

在 Matplotlib 中，默认网格是一组与 x 轴和 y 轴上的主要刻度线对齐的主要网格线。

In Matplotlib, the default grid is a set of major gridlines that align with the major tick marks on both the x-axis and the y-axis.

Example

在此示例中，我们创建了一个基本的正弦波绘图并添加了默认网格。

In this example, we create a basic sine wave plot and add the default grid.

import matplotlib.pyplot as plt
import numpy as np

# Create some data
x = np.linspace(0, 2 * np.pi, 100)
y = np.sin(x)

# create a plot
fig, ax = plt.subplots(figsize=(7,4))

# Plot the data
plt.plot(x, y)

# Add grid
ax.grid(True)

# set the title
ax.set_title('Basic Plot with Grids')

# Show 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 −

grids ex1

Customizing Grid

自定义网格线包括线型、线宽、颜色和透明度。

Customizing gridlines includes linestyle, linewidth, color, and transparency.

Example

此示例演示如何通过更改其线型、线宽、颜色和透明度来自定义网格线。

This example demonstrates how to customize the gridline by changing its linestyle, linewidth, color, and transparency.

import matplotlib.pyplot as plt
import numpy as np

# Create some data
x = np.arange(0, 1, 0.05)
y = x**2

# Create the plot
fig, ax = plt.subplots(figsize=(7,4))

# Plot the data
plt.scatter(x, y)

# Customize grid
ax.grid(True, linestyle='-.', linewidth=1, color='red', alpha=0.9)

# set the title
ax.set_title('Customizing Grids')

# Show 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 −

grids ex2

Adding Minor Gridlines

Example

此示例演示如何将主网格线和次网格线全部添加到绘图中。

This example demonstrates how to add both the major and minor gridlines to a plot.

import matplotlib.pyplot as plt
import numpy as np

# Create some data
x = np.arange(0, 1, 0.05)
y = x**2

# Create the plot
fig, ax = plt.subplots(figsize=(7,4))

# Plot the data
plt.scatter(x, y)

# Add major grid
ax.grid(True)

# Add minor grid
ax.minorticks_on()
ax.grid(which='minor', linestyle=':', linewidth=0.5, color='red', alpha=0.5)

# set the title
ax.set_title('Major and Minor Gridlines')

# Show 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 −

grids ex3

Manually adding the grids

此方法涉及明确指定垂直线和水平线的位置。通过遍历特定的间隔或值，用户可以在所需位置绘制网格线。这涉及使用类似 pyplot.axvline() 和 pyplot.axhline() 的函数分别绘制垂直线和水平线。

This approach involves explicitly specifying the positions of vertical and horizontal lines. By iterating through specific intervals or values, users can draw gridlines at desired locations. This involves using functions like pyplot.axvline() and pyplot.axhline() to draw vertical and horizontal lines, respectively.

Example

以下是一个手动在 x 轴上每三个点绘制垂直网格线的示例。

Here is an example that manually draws vertical grid lines at every third point on the x-axis.

import matplotlib.pyplot as plt
import numpy as np

# Create some data
x = np.arange(0, 1, 0.05)
y = x**2

# Create the plot
plt.subplots(figsize=(7,4))

# Plot the data
plt.scatter(x, y)

# Set x and y tick locations
plt.xticks(np.arange(0, 1.01, 0.1))
plt.yticks(np.arange(0, 1.01, 0.1))
plt.title('Manually Drawing the Grids ')

# Draw grid lines for every third point on the x-axis
for pt in np.arange(0, 1.01, 0.3):
   plt.axvline(pt, lw=0.5, color='black', alpha=0.5)

# Show 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 −

grids ex4

Hiding the gridlines

可以通过向 grid() 函数指定布尔值 False 来隐藏或删除绘图中的网格线。

Hiding or removing the gridlines in a plot can be achieved by specifying the boolean value False to the grid() function.

Example

以下是一个隐藏绘图的网格线和轴（X 轴和 Y 轴）的示例。

Here is an example that hide gridlines and axes (X and Y axis) of a plot.

import numpy as np
import matplotlib.pyplot as plt

#  Create a figure
fig = plt.figure(figsize=(7, 4))

# Generate data
x = np.linspace(-10, 10, 50)
y = np.sin(x)

# Plot horizontal line
plt.axhline(y=0, c="green", linestyle="dashdot", label="y=0")

# Plot sine curve
plt.plot(x, y, c="red", lw=5, linestyle="dashdot", label="y=sin(x)")

# Hide gridlines
plt.grid(False)

# Hide axes
plt.axis('off')

# Add legend
plt.legend()

# Show plot
plt.show()

执行上述代码时，您将获得以下输出 -

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

grids ex5

Gridlines Across The Subplots

在多个子图中比较数据时，跨所有子图绘制网格线很有用，以在绘图之间保持可视比较。

When comparing data across multiple subplots, it’s useful to have gridlines across all subplots to maintain visual comparisons between plots.

Example

以下是一个演示如何跨子图绘制网格线的示例。

Here is an example that demonstrates how to plot grids across subplots.

import matplotlib.pyplot as plt

# Data
d = [1, 2, 3, 4, 5, 6, 7, 8, 9]
f = [0, 1, 0, 0, 1, 0, 1, 1, 0]

# Create figure and subplots
fig = plt.figure(figsize=(7,4))
fig.set_size_inches(30, 10)
ax1 = fig.add_subplot(211)
ax2 = fig.add_subplot(212)

# Plot data on subplots
ax1.plot(d, marker='.', color='b', label="1 row")

# Draw grid lines behind bar graph
ax2.bar(range(len(d)), d, color='red', alpha=0.5)

# Enable grids on both subplots
ax1.grid()
ax2.grid()

# Display the plot
plt.show()

执行上述代码时，您将获得以下输出 -

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

grids ex6