Solutions to common problems in visualization (IX) background color

Background color problem

One . Preface

In the process of data visualization , We usually encounter the problem of changing the color of Beijing , Today, let's study together in matploltlib The color of one canvas in the changes .

Two . Solution

matplotlib A canvas is made up of a figure and axes form .

2.1 change figure Color

every last Figure Objects all have one patch attribute , Store his Beijing Rectangle object , Get Association Rectangle Use after object set_color() Method to set the background color .

Rectangle Class explanation

import matplotlib.pyplot as plt

figure, ax = plt.subplots(1, 1)
patch = figure.patch
patch.set_color("red")

plt.show()

Change effect ：

2.2 change axes The background color

Empathy , every last Axes Objects are also associated with a Rectangle object , Use the same method to change the background color . The code is as follows ：

import matplotlib.pyplot as plt

import numpy as np

figure, ax = plt.subplots(1, 1)
patch = ax.patch
patch.set_color("blue")

plt.show()

The effect is as follows ：

2.3 Advanced - The background uses a gradient

The background color can not only use solid color, but also use gradient color , The principle that it implements is to use imshow Method to draw a gradient background on the background , And modify his transparency , So you can draw on the gradient background . However, it should be noted that if the background transparency is too large, it will have a great impact on the actual drawing .

import matplotlib.pyplot as plt

import numpy as np

figure, ax = plt.subplots(1, 1)
patch = ax.patch
patch.set_color("blue")

x = np.arange(200)
y = np.arange(200)
_, yv = np.meshgrid(x, y)
im = ax.imshow(yv, interpolation='bicubic',cmap="PuOr",
               vmin=0, vmax=200, alpha=0.5)

plt.plot([1, 100], [30, 150], color='k')
plt.show()

The effect is as follows ：

3、 ... and . Reference resources

1. Solution to the problem of cylinder annotation
2. linestyle Parameters,
3. capstyle Parameters,
4. joinstyle Parameters,
5. Solution to subgraph spacing problem
6. Subgraph setting headline solution
7. Drawing scale setting solution
8. Mathematical formula problem