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今天小编给大家带来MATLAB三维绘图(b)，

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本期推文阅读时长大约6分钟，请您耐心阅读。

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Dear you,

This is the LearningYard Academy!

Today,the editor brings you MATLAB three-dimensional drawing (b),

Welcome your visit!

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一、三维绘图函数及工具

除了绘制二维图形，MATLAB还提供了一系列强大的三维图形绘制函数，这些函数的分类列表如上图所示。可以看出，MATLAB基本的三维图形包括网格型（mesh）、面型（surface）、方向矢量型（direction）等多种类型。上一期分享中我们学习了plot3三维图像函数、surf三维曲面图像函数、mesh函数和waterfall函数，接着我们继续学习三维条形图、三维球体图、三维饼形图、三维箭状图等。

In addition to drawing two-dimensional graphics, MATLAB also provides a series of powerful three-dimensional graphics drawing functions, the classification list of these functions is shown in the figure above. It can be seen that the basic three-dimensional graphics of MATLAB include mesh, surface, direction and other types. In the previous sharing, we learned the plot3 three-dimensional image function, the surf three-dimensional surface image function, the mesh function and the waterfall function, and then we continued to learn the three-dimensional bar chart, the three-dimensional sphere chart, the three-dimensional pie chart, the three-dimensional arrow chart, etc.

二、实例分析演示

1.三维条形图

在MATLAB中，可以使用函数bar3和bar3h来绘制三维条形，bar3函数绘制三维条形图，常用格式为：

In MATLAB, you can use the functions bar3 and bar3h to draw three-dimensional bars, and the bar3 function draws three-dimensional bar graphs. The common format is:

bar3(y)

bar3(x,y)

【例1】使用bar3和bar3h函数绘制条形图示例。

[Example 1] An example of drawing a bar chart using the bar3 and bar3h functions.

X=rand(5,5)*10;

subplot(221),bar3(X,'detached'),title('detached');

subplot(222),bar3(X,'grouped'),title('grouped');

subplot(223),bar3h(X,'stacked'),title('stacked');

subplot(224),bar3h(X,'detached'),title('detached');

以上代码运行的结果如图所示：

The result of running the above code is shown in the figure:

2.三维球体图

MATLAB提供了sphere函数来生成三维球体图。

MATLAB provides the sphere function to generate a three-dimensional sphere map.

【例2】sphere函数使用示例。

[Example 2] Example of using the sphere function.

subplot(2,2,1)

sphere(8) % 括号中的数字指生成球体的面数，这里是指8×8

axis equal

subplot(2,2,2)

sphere(16)

axis equal

subplot(2,2,3)

sphere(24)

axis equal

subplot(2,2,4)

sphere(32)

axis equal

以上代码运行的结果如图所示：

The result of running the above code is shown in the figure:

3.三维饼形图

函数pie3用于绘制三维饼形图，其用法与二维饼形图函数pie基本相同，pie3函数绘制三维饼图，常用格式为：

The function pie3 is used to draw a three-dimensional pie chart, and its usage is basically the same as that of the two-dimensional pie chart function pie，The pie3 function draws a three-dimensional pie chart. The common format is:

pie3(x)

【例3】使用函数pie3绘制三维饼形图。

[Example 3] Use the function pie3 to draw a three-dimensional pie chart.

x=rand(1,5); % 产生一个含有5个0~1之间的随机数构成的向量

explode=[0 1 0 0 0]; % 分离出向量x的第二个元素

pie3(x,explode)

以上代码运行的结果如图所示：

The result of running the above code is shown in the figure:

4.三维箭状图

函数quiver3用来绘制三维的箭状图或速度矢量图，其用法和quiver类似。

The function quiver3 is used to draw a three-dimensional arrow diagram or a velocity vector diagram, and its usage is similar to that of quiver.

【例4】绘制曲面图片的曲面法线。

[Example 4] Draw the surface normal of the surface image.

[X,Y] = meshgrid(-2:0.25:2,-1:0.2:1);

Z = X.* exp(-X.^2 - Y.^2);

[U,V,W] = surfnorm(X,Y,Z);

quiver3(X,Y,Z,U,V,W,0.5);

hold on

surf(X,Y,Z);

colormap hsv

view(-35,45)

axis ([-2 2 -1 1 -.6 .6])

hold off

以上代码运行的结果如图所示：

The result of running the above code is shown in the figure:

5.三维等高线图

contour3函数用于绘制一个矩阵的三维等高线图，其用法与contour函数基本相同。

The contour3 function is used to draw a three-dimensional contour plot of a matrix, and its usage is basically the same as the contour function.

【例5】绘制函数图片的等高线图形，并使用cool颜色图。

[Example 5] Draw the contour graph of the function picture and use the cool color map.

[X,Y] = meshgrid([-2:.25:2]); % 生成维数相同的两个矩阵X，Y

Z = X.*exp(-X.^2-Y.^2);

contour3(X,Y,Z,40) % 绘制Z的等高线，40为等高线的数目

surface(X,Y,Z,'EdgeColor',[.8 .8 .8],'FaceColor','none')% 绘制表面图

grid off % 去掉网格线

view(-15,25) % 设定视角

colormap cool % 建立颜色图

以上代码运行的结果如图所示：

The result of running the above code is shown in the figure:

今天的分享就到这里了。

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让我们相约明天，

祝您今天过得开心快乐！

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Let us meet tomorrow,

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参考资料：谷歌翻译、哔哩哔哩

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文案 |Yuan

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