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Add text description
Many times we need to add descriptive text to the graph to highlight the importance of points or lines in the graph.
import numpy as np
import matplotlib.pyplot as plt
x = np.linspace(0.8.1000)
y = 2.0 * x + 0.5 * 5 * x ** 2
plt.title('Acceleration Moving')
plt.xlabel('Time')
plt.ylabel('distance')
plt.scatter(x[0],y[0])
plt.text(x[0], y[0].'start')
plt.plot(x, y, c = 'c')
plt.show()
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The Tips: plt.text() function takes the location and text to display as arguments. The position is given in coordinates that specify the position of the lower-left corner of the text box.
Alignment of text
The text is surrounded by an implicit text box (shown below) that aligns the text relative to the coordinates passed to plt.text(). Use the Verticalalignment and Horizontalalignment parameters (which can be abbreviated va and HA, respectively) to control the alignment. The vertical alignment options are as follows:
| The parameter value | instructions |
|---|---|
| center | Parameter coordinates relative to the center of the text box |
| top | Parameter coordinates relative to the upper side of the text box |
| bottom | Parameter coordinates relative to the bottom of the text box |
| baseline | Parameter coordinates relative to the baseline of the text |
import numpy as np
import matplotlib.pyplot as plt
x = np.linspace(0.8.1000)
y = 2.0 * x + 0.5 * 5 * x ** 2
x_b = np.linspace(0.8.1000)
y_b = np.zeros_like(x_b)
plt.title('Acceleration Moving')
plt.xlabel('Time')
plt.ylabel('distance')
plt.scatter(x[0],y[0])
plt.text(0.0.'center', va='center')
plt.text(2.0.'top', va='top')
plt.text(4.0.'bottom', va='bottom')
plt.text(6.0.'baseline', va='baseline')
plt.plot(x, y, c = 'c')
plt.plot(x_b, y_b, c = 'm')
plt.show()
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The horizontal alignment options are as follows:
| The parameter value | instructions |
|---|---|
| center | Parameter coordinates relative to the center of the text box |
| left | Parameter coordinates relative to the left of the text box |
| right | Parameter coordinates relative to the right of the text box |
import numpy as np
import matplotlib.pyplot as plt
x = np.linspace(0.8.1000)
y = 2.0 * x + 0.5 * 5 * x ** 2
y_b = np.linspace(0.100.1000)
x_b = np.zeros_like(y_b)
plt.title('Acceleration Moving')
plt.xlabel('Time')
plt.ylabel('distance')
plt.scatter(x[0],y[0])
plt.text(0.0.'center', ha='center')
plt.text(0.50.'left', ha='left')
plt.text(0.100.'right', ha='right')
plt.plot(x, y, c = 'c')
plt.plot(x_b, y_b, c = 'm')
plt.show()
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Text bounding box
In order to explicitly draw a text box, plt.plot() supports a bbox in the form of a dictionary, which defines the appearance configuration of the text box:
import numpy as np
import matplotlib.pyplot as plt
x = np.linspace(0.8.1000)
y = 2.0 * x + 0.5 * 5 * x ** 2
box = {
'facecolor': '75'.'edgecolor': 'r'.'boxstyle': 'round'
}
plt.title('Acceleration Moving')
plt.text(0.8.'start', bbox=box)
plt.plot(x, y, c = 'c')
plt.show()
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The dictionary definition for the bbox argument contains the following common key-value pairs:
| key | Description and optional values |
|---|---|
| facecolor | Used to set the color of the text box background and edge |
| edgecolor | Used to set the color of the text box edge |
| alpha | Used to set the transparency level to better blend the text box with the background |
| boxstyle | Sets the style of the text box. Options include “round” and “square” |
| pad | If “boxstyle” is set to “square”, it defines the amount of padding between the text and the edges of the text box |
Series of links
Matplotlib common statistical graph drawing
Matplotlib uses custom colors to draw statistics
Matplotlib controls line style and line width
Matplotlib custom style to draw beautiful statistics