How to draw contours and 3D Images based on python and Matplotlib
This article mainly introduces how to draw contours and three-dimensional images based on python and Matplotlib, which has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let Xiaobian take you to understand.
The function drawn in this example is:
1. Grid point
takes a look at the drawing of grid points before drawing a curve. For example, to draw a 3x3 grid, you need nine coordinate points:
(0pr 2)-(1pr 2)-(2pr 2)
(0pr 1)-(1jr 1)-(2pr 1)
(0) (0)-(1) (1)-(2)
represents its x-axis and y-axis coordinates separately:
# x axis: [[0,1,2], [0,1,2], [0,1,2]] # y axis: [[0,0,0], [1,1,1], [2,2,2]]
can use np.meshgrid () in numpy to generate grid points:
Import numpy as npimport matplotlib.pyplot as plt# 10x10x = np.linspace (- 1.5,1.5, num=10) y = np.linspace (- 1.5,1.5, num=10) # generate gridX, Y = np.meshgrid (x, y) plt.plot (X, Y, marker='.', linestyle='') plt.grid (True) plt.show ()
two。 Contour line
The coordinate position of the data points needed by to draw the contours (XMague y) and the height z of the coordinates z, which is calculated by bringing the coordinate points (XMague y) into the function f (XMago y) f (XMagy) f (XPY). In matplotlib, you can use plt.contour () to draw:
Import numpy as npimport matplotlib.pyplot as pltx = np.linspace (- 1.5,1.5, num=100) y = np.linspace (- 1.5,1.5, num=100) X, Y = np.meshgrid (x, y) f = X* np.exp (- X, y) fig = plt.figure () plt.xlim (- 1.5,1.5) plt.ylim (- 1.5,1.5) # drawax = plt.contour (X, Y, f, levels=10 Cmap=plt.cm.cool) # add labelplt.clabel (ax, inline=True) # plt.savefig ('img1.png') plt.show ()
# add colorplt.contourf (X, Y, f, levels=10, cmap=plt.cm.cool) # plt.colorbar () # plt.savefig ('img1.png') plt.show ()
For more api parameters of , please refer to the official documentation.
3. Three-dimensional image
The 3D image of the function needs the same data as the contours, that is, the coordinate position (x, y) and the height z of the coordinates. In matplotlib, you can use mpl_toolkits.mplot3d to draw:
Import numpy as npimport matplotlib.pyplot as pltfrom mpl_toolkits.mplot3d import Axes3Dx = np.linspace (- 1.5,1.5, num=100) y = np.linspace (- 1.5,1.5, num=100) X, Y = np.meshgrid (x, y) f = X* np.exp (- X, y) fig = plt.figure () ax = Axes3D (fig) plt.xlim (- 1.5,1.5) plt.ylim (- 1.5,1.5) ax.plot_surface (X, Y, f Cmap=plt.cm.cool) # plt.savefig ('img1.png') plt.show ()
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