Matplotlib 简明教程
Matplotlib - Unit Handling
What is Unit Handling?
在 Matplotlib 库中，单元处理是指库管理和解释不同类型的单元的能力，以准确地绘制数据。Matplotlib 允许用户指定和使用各种单元来定义和显示绘图中的数据，无论它们是否与长度、时间、角度或其他物理量有关。
In Matplotlib library unit handling refers to the capability of the library to manage and interpret different types of units for plotting data accurately. Matplotlib allows users to specify and work with various units for defining and displaying data on plots whether they are related to length, time, angle or other physical quantities.
Key Aspects of Unit Handling in Matplotlib
以下是 matplotlib 库中单元处理的关键方面。
The below are the key aspects of unit handling in matplotlib library.
Support for Various Units
Matplotlib 支持多个单元，例如像素、英寸、厘米、磅、图形尺寸的几分之几等。这种灵活性允许用户使用他们选择的单元来定义绘图元素，如位置、大小和间距。
Matplotlib supports multiple units such as pixels, inches, centimeters, points, fractions of the figure size and more. This flexibility allows users to define plot elements like positions, sizes and spacing using the unit of their choice.
Functions and Techniques for Unit Handling
有一些技术和函数可用于单元处理。
There are few techniques and functions available for unit handling.
Automatic Conversion
Matplotlib 自动处理单元转换以绘制数据。当使用 plot() 函数或其他绘制函数时，库会根据所选坐标系将数据单元转换为显示单元。
Matplotlib automatically handles unit conversion for plotting data. When using plot() function or other plotting functions the library converts data units to display units based on the chosen coordinate system.
这种自动转换简化了在 Matplotlib 中绘制数据的过程，因为它处理了不同单元之间的转换，而不需要用户进行明确的转换步骤。以下是演示单元处理中自动转换的示例。
This automatic conversion simplifies the process of plotting data in Matplotlib by handling the conversion between different units without requiring explicit conversion steps from the user. Here’s an example demonstrating auto-conversion in unit handling.
import matplotlib.pyplot as plt
# Sample data in different units
time_seconds = [1, 2, 3, 4, 5] # Time in seconds
distance_meters = [2, 4, 6, 8, 10] # Distance in meters
plt.plot(time_seconds, distance_meters) # Matplotlib handles unit conversion
plt.xlabel('Time (s)')
plt.ylabel('Distance (m)')
plt.title('Auto-Conversion of Units in Matplotlib')
plt.show()
Axis Labeling
在轴标签中，我们分别使用 xlabel() 和 ylabel() 函数对 x 轴和 y 轴进行标签。这些函数允许我们在轴标签中指定单元。
In Axis labeling we use xlabel() and ylabel() functions to label the x-axis and y-axis respectively. These functions allow us in specifying units for the axis labels.
我们可以根据要绘制的数据单位适当调整标签。这种做法可以帮助为任何查看图形的人提供绘图数据的背景和清晰度。以下是一个演示如何使用 Matplotlib 为带单位的轴添加标签的示例。
We can adjust the labels accordingly to match the units of the data being plotted. This practice helps provide context and clarity to the plotted data for anyone viewing the graph. The below is an example demonstrating how to label axes with units using Matplotlib.
import matplotlib.pyplot as plt
# Sample data
time = [0, 1, 2, 3, 4] # Time in seconds
distance = [0, 10, 20, 15, 30] # Distance in meters
# Creating a plot
plt.plot(time, distance)
# Labeling axes with units
plt.xlabel('Time (s)')
plt.ylabel('Distance (m)')
plt.title('Distance vs. Time')
plt.show()
Custom Units
对于更明确的控制，可以使用轴方法 set_units() 和 ax.xaxis.set_units() ，以明确设置 x 轴和 y 轴的单位。
For more explicit control set_units() methods for axes ax.xaxis.set_units() and ax.yaxis.set_units() can be used to explicitly set the units for the x-axis and y-axis.
此自定义轴单位处理确保图形使用特定单位（例如时间的小时、距离的公里等）显示数据，并相应地给轴添加标签，为可视化提供背景和清晰度。以下是一个演示 Matplotlib 中自定义轴单位处理的示例。
This custom axis unit handling ensures that the plot displays the data using specific units such as hours for time, kilometers for distance etc and labels the axes accordingly providing context and clarity to the visualization. Here’s an example demonstrating custom axis unit handling in Matplotlib.
import matplotlib.pyplot as plt
# Sample data
time_hours = [1, 2, 3, 4, 5] # Time in hours
distance_km = [50, 80, 110, 140, 170] # Distance in kilometers
fig, ax = plt.subplots()
# Plotting the data
ax.plot(time_hours, distance_km)
# Customizing x-axis and y-axis units
ax.xaxis.set_units('hours') # Set x-axis units to hours
ax.yaxis.set_units('km') # Set y-axis units to kilometers
# Labeling axes with units
ax.set_xlabel('Time')
ax.set_ylabel('Distance')
ax.set_title('Distance over Time')
plt.show()
Unit Conversion
plt.gca() 中的 convert_xunits() 和 convert_yunits() 等函数可以将数据单位转换为显示单位。以下是一个演示 Matplotlib 中单位处理中单位转换的示例。
Functions like convert_xunits() and convert_yunits() within plt.gca() can convert data units to display units. Here is an example demonstrating unit conversion in unit handling in Matplotlib
import matplotlib.pyplot as plt
# Specify figure size in inches
plt.figure(figsize=(6, 4)) # Width: 6 inches, Height: 4 inches
# Set x-axis label with different units
plt.xlabel('Distance (cm)') # Using centimeters as units
# Plotting data with specific units
x = [1, 2, 3, 4]
y = [10, 15, 12, 18]
plt.plot(x, y)
plt.title('Plot with Unit Handling')
plt.show()
Use Cases for Unit Handling
Consistency in Measurement - 确保标签、注释和绘图元素中的单位一致，以提高清晰度。
Consistency in Measurement − Ensuring consistent units across labels, annotations and plot elements for clarity.
Dimension-Agnostic Plotting - 无论单位类型（例如长度、时间等）如何，都可以使用 Matplotlib 绘制数据，并适当地处理转换和缩放。
Dimension-Agnostic Plotting − Plotting data regardless of the unit type such as length, time etc. with Matplotlib handling conversions and scaling appropriately.
Customization Flexibility - 允许用户使用他们首选的单位定义绘制属性，以更好地控制可视化效果。
Customization Flexibility − Allowing users to define plot attributes using their preferred units for better control over visualizations.