matlab函数绘图三维（宏记软件四）

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今天小编为大家带来Matlab三维绘图及gtext函数.

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本期推文阅读时长大约5分钟，请您耐心阅读。

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Today, the editor brings Matlab 3D drawing and gtext function.

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The reading time of this tweet is about 5 minutes, please read it with patience.

大家好，本期推文将介绍几种三维绘图的方式和gtext函数，一起来看。

Hello everyone, this tweet will introduce several 3D drawing methods and gtext functions, let's take a look.

1.圆柱图

Matlab里面一般用cylinder创建圆柱数据，用surf 或 mesh 函数绘制出三维图。绘制方法如下：

左边代码为：

t = 0:pi/20:2*pi;

r = 4 sin(t);

[X,Y,Z] = cylinder(r);

surf(X,Y,Z)

xlabel('x')

ylabel('y')

zlabel('z')

代码含义为t在0π—2π中每隔20分之一π取一点，然后对半径r赋值:r=4 sin(t)，然后以原点为底面中心绘制圆柱，并标上X，Y，Z坐标轴。

1. Cylindrical diagram

In Matlab, cylinder is generally used to create cylinder data, and surf or mesh functions are used to draw three-dimensional graphs. The drawing method is as follows:

The code on the left is:

t = 0:pi/20:2*pi;

r = 4 sin(t);

[X,Y,Z] = cylinder(r);

surf(X,Y,Z)

xlabel('x')

ylabel('y')

zlabel('z')

The meaning of the code is that t takes a point every 1/20 of π in 0π—2π, and then assigns a value to the radius r: r=4 sin(t), then draws a cylinder with the origin as the center of the bottom surface, and marks X, Y, Z coordinate axis.

2.条带图

Matlab中绘制条带图一般使用ribbon函数绘制。构建数据一般使用 peaks 函数， peaks 函数是通过平移和缩放高斯分布获得的公式，在绘制三维图中比较实用。绘制方法如下：

左边代码为：

[x,y] = meshgrid(-3:0.25:3,-3:0.2:3);

z = peaks(x,y);

ribbon(y,z)

代码的含义为x在-3到3的过程中每隔0.25取一点，y在-3到3的过程中每隔0.2取一点，然后用meshgrid 函数将 x 和 y 两个向量指定地域转换为矩阵 X 和 Y。再用peaks(x,y)函数对高度z进行赋值。最后通过ribbon函数输出。如下图：

2. Strip chart

The strip chart in Matlab is generally drawn using the ribbon function. The peaks function is generally used to construct the data. The peaks function is a formula obtained by translating and scaling the Gaussian distribution, which is more practical for drawing 3D graphs. The drawing method is as follows:

The code on the left is:

[x,y] = meshgrid(-3:0.25:3,-3:0.2:3);

z = peaks(x,y);

ribbon(y,z)

The meaning of the code is that x takes a point every 0.25 in the process of -3 to 3, and y takes a point every 0.2 in the process of -3 to 3, and then use the meshgrid function to convert the fields specified by the two vectors of x and y into Matrices X and Y. Then use the peaks(x,y) function to assign the height z. Finally, it is output through the ribbon function. As shown below:

3. 三维等高线图

在matlab中一般用contour3函数绘制三维等高线图。使用方法如下：

左边代码为：

[X,Y] = meshgrid(-5:0.5:5);

Z = X.^2 Y.^2;

contour3(Z)

代码含义为：代码的含义为x，y都在-5到5的过程中每隔0.5取一点，然后用meshgrid 函数将 x 和 y 两个向量指定的域转换为矩阵 X 和 Y。对高度Z进行赋值Z=X2 Y2。最后绘制等高线。在这个例子中，让软件随机选择 x 和 y 轴的等高线和范围。

3. 3D contour map

In matlab, the contour3 function is generally used to draw a three-dimensional contour map. The method of use is as follows:

The code on the left is:

[X,Y] = meshgrid(-5:0.5:5);

Z = X.^2 Y.^2;

contour3(Z)

The meaning of the code is: the meaning of the code is that x and y are taken every 0.5 points in the process of -5 to 5, and then the meshgrid function is used to convert the fields specified by the two vectors of x and y into matrices X and Y. Assign the value Z=X2 Y2 to the height Z. Finally draw the contour lines. In this example, let the software randomly choose the contours and ranges for the x and y axes.

4. gtext函数

在matlab中，gtext函数可以使用鼠标将文本添加到图窗，一般应用于二维的图窗中。使用方法如下：

左边代码为：

plot(3:45)

t = gtext('matlab learning')

代码含义为：使用plot函数绘制3：45的二维图窗，然后使用gtext函数将“matlab learning”贴在鼠标选取的位置。

4. gtext function

In matlab, the gtext function can use the mouse to add text to figures, generally used in two-dimensional figures. The method of use is as follows:

The code on the left is:

plot (3:45)

t = gtext('matlab learning')

The meaning of the code is: use the plot function to draw a 3:45 two-dimensional figure, and then use the gtext function to paste "matlab learning" at the position selected by the mouse.

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参考资料：谷歌翻译

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