【 MATLAB 】legend 的使用简析
【摘要】 目录
legend
在作图命令中（plot）给出图例标签；
legend(label1,...,labelN)
给当前轴添加图例；
legend(target,___)
给特定轴添加图例；
legend(subset,___)
给部分函数添加图例；
legend(___,'Location',lcn)
指定图例的位置（方向）以及显示的列数；
lgd&nb...
目录
MATLAB 中 legend 可以翻译为图例，下面逐一用例子来说明 legend 的用法，并辅以必要的说明。
我只挑选几种使用的来说明。
legend
在作图命令中（plot）给出图例标签；
Plot two lines. Specify the legend labels during the plotting commands by setting the DisplayName property to the desired text. Then, add a legend.
画两条线。 通过将DisplayName属性设置为所需文本，在绘图命令期间指定图例标签。 然后，添加一个图例（legend）。
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% Plot two lines.
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% Specify the legend labels during the plotting commands by setting the DisplayName property to the desired text.
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% Then, add a legend.
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clear
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clc
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close all
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x = linspace(0,pi);
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y1 = cos(x);
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plot(x,y1,'DisplayName','cos(x)')
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hold on
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y2 = cos(2*x);
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plot(x,y2,'DisplayName','cos(2x)')
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hold off
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legend
对代码做如下改动，将两幅图分开画，然后添加图例的方法：
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% Plot two lines.
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% Specify the legend labels during the plotting commands by setting the DisplayName property to the desired text.
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% Then, add a legend.
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clear
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clc
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close all
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x = linspace(0,pi);
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y1 = cos(x);
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subplot(2,1,1);
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plot(x,y1,'DisplayName','cos(x)')
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legend
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%hold on
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y2 = cos(2*x);
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subplot(2,1,2);
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plot(x,y2,'DisplayName','cos(2x)')
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% hold off
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legend
legend(label1,...,labelN)
label1,...,labelN)给当前轴添加图例；
legend( sets the legend labels. Specify the labels as a list of character vectors or strings, such as label1,...,labelN)legend('Jan','Feb','Mar').
legend（label1，...，labelN）设置图例标签。 将标签指定为字符向量或字符串列表，例如legend（'Jan'，'Feb'，'Mar'）。
绘制两条线并在当前轴上添加图例。 将图例标签指定为图例功能的输入参数。
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% Plot two lines and add a legend to the current axes.
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% Specify the legend labels as input arguments to the legend function.
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clear
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clc
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close all
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x = linspace(0,pi);
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y1 = cos(x);
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plot(x,y1)
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hold on
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y2 = cos(2*x);
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plot(x,y2)
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legend('cos(x)','cos(2x)')
将程序稍作改动，将这两个正弦函数的图像画在不同的子图中，并添加标签：
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% Plot two lines and add a legend to the current axes.
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% Specify the legend labels as input arguments to the legend function.
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clear
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clc
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close all
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x = linspace(0,pi);
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y1 = cos(x);
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subplot(2,1,1);
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plot(x,y1)
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legend('cos(x)')
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% hold on
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y2 = cos(2*x);
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subplot(2,1,2);
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plot(x,y2)
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legend('cos(2x)')
legend(target,___)
给特定轴添加图例；
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% Create a figure with two subplots and return the two Axes objects, ax1 and ax2.
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% Plot random data in each subplot. Add a legend to the upper subplot by specifying ax1 as the first input argument to legend.
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clear
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clc
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close all
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x = linspace(0,pi);
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y1 = rand(3);
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ax1 = subplot(2,1,1);
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plot(y1)
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y2 = rand(5);
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ax2 = subplot(2,1,2);
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plot(y2)
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legend(ax1,{'Line 1','Line 2','Line 3'})
legend(subset,___)
给部分函数添加图例；
subset 是子集的意思，它表示只给这个子集中的函数添加图例，后面的——表示，这些图例的标签，即它们的名字是什么？
下面给出一个实例，参考起来很容易理解：
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% If you do not want to include all of the plotted graphics objects in the legend,
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% then you can specify the graphics objects that you want to include.
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% Plot three lines and return the Line objects created.
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% Create a legend that includes only two of the lines.
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% Specify the first input argument as a vector of the Line objects to include.
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clear
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clc
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close all
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x = linspace(0,pi);
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y1 = cos(x);
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p1 = plot(x,y1);
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hold on
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y2 = cos(2*x);
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p2 = plot(x,y2);
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y3 = cos(3*x);
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p3 = plot(x,y3);
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hold off
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legend([p1 p3],{'cos(x)','cos(3x)'})
legend(___,'Location',lcn)
指定图例的位置（方向）以及显示的列数；
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% Plot four lines. Create a legend in the northwest area of the axes.
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% Specify the number of legend columns using the NumColumns property.
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clear
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clc
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close all
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x = linspace(0,pi);
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y1 = cos(x);
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plot(x,y1)
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hold on
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y2 = cos(2*x);
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plot(x,y2)
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y3 = cos(3*x);
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plot(x,y3)
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y4 = cos(4*x);
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plot(x,y4)
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hold off
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legend({'cos(x)','cos(2x)','cos(3x)','cos(4x)'},'Location','northwest','NumColumns',2)
lgd = legend(___)
给图例添加标题；
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% Plot two lines and create a legend. Then, add a title to the legend.
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clear
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clc
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close all
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x = linspace(0,pi);
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y1 = cos(x);
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plot(x,y1)
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hold on
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y2 = cos(2*x);
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plot(x,y2)
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hold off
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lgd = legend('cos(x)','cos(2x)');
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title(lgd,'My Legend Title')
legend('boxoff')
去除图例边框；
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% Plot two lines and create a legend in the lower left corner of the axes.
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% Then, remove the legend background and outline.
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clear
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clc
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close all
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x = linspace(0,pi);
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y1 = cos(x);
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plot(x,y1)
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hold on
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y2 = cos(2*x);
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plot(x,y2)
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hold off
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legend({'cos(x)','cos(2x)'},'Location','southwest')
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legend('boxoff')
Modify Legend Appearance
修改图例的外观；
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% Modify the legend appearance by setting Legend properties.
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clear
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clc
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close all
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rdm = rand(4);
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plot(rdm)
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lgd = legend({'Line 1','Line 2','Line 3','Line 4'},'FontSize',12,'TextColor','blue')
当然也可以通过下面的方式来修改：
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% Modify the legend appearance by setting Legend properties.
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clear
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clc
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close all
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rdm = rand(4);
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plot(rdm)
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lgd = legend('Line 1','Line 2','Line 3','Line 4');
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lgd.FontSize = 12;
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lgd.TextColor = 'blue';
效果是一样的。
下面多改几下：
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% Modify the legend appearance by setting Legend properties.
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clear
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clc
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close all
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rdm = rand(4);
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plot(rdm)
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lgd = legend('Line 1','Line 2','Line 3','Line 4');
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lgd.FontSize = 12;
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lgd.TextColor = 'blue';
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lgd.NumColumns = 2;
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lgd.Location = 'southwest';
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leg.Orientation = 'vertical';
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title(lgd,'My Legend Title');
文章来源: reborn.blog.csdn.net，作者：李锐博恩，版权归原作者所有，如需转载，请联系作者。
原文链接：reborn.blog.csdn.net/article/details/82857626
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