如何为MATLAB errorbar plot的点和垂直线设置不同的图例？

Question

我有errorbar图表显示平均值和标准差。我希望有一个圈子的传奇项目，平均值，以及一个单独的栏。像，

--------------------------
| o mean                 |
| | standard deviation   |
--------------------------

MWE

errorbar([1 2], [2 3], [0.1 0.2], 'o');
legend('mean +- stddev', 'Location','north')

给了我这个

Answer 1

这样做的一种方法是添加一条不可见的线条。试试这个：

errorbar([1 2], [2 3], [0.1 0.2], 'o');
hold on;
plot(1,3,'-b');
legend('Mean','Standard deviation','Location','north');

Answer 2

这建立在Jens Boldsen's answer之上，并添加以下内容：

• 可以旋转表示图例中错误栏的线条，使其垂直，或保持默认水平方向;
• 该行的末尾是＆＃34;关闭＆＃34; 短线。

该方法非常通用，因为它支持：

• 任意颜色， linestyle 和标记作为errorbar的参数。请注意，实际条形图始终绘制为实线，没有标记（使用指定的颜色）。这是按errorbar行为。
• 新创建的短线随图例移动。
• 这些行的宽度是可配置参数。此外，errobar的长度是垂直情况下的参数。两者都以相对于图例的标准化单位定义。

由于R2014b中引入的图形对象的变化，该方法略有不同，具体取决于Matlab版本。此外，图例中的errobar线可以是水平的或垂直的。 所以有四个案例。

案例I：Pre-R2014b，图例中的水平误差栏

绘制完数据和图例后，代码将遵循以下步骤：

1. 获取传奇的孩子
2. 在这些孩子中找到合适的行
3. 获取 x 和 y 坐标
4. 利用这些坐标，在每一端创建两条短线。将这些线条作为传奇的子项，以便它们随之移动。

该代码已在Matlab R2010b中进行了测试。

%// Define graph aspect
color_spec = 'r';       %// color of data and bars.
linestyle_spec = '--';  %// linestyle for data. The bars are always solid
marker_spec = 'o';      %// marker for data
wid = .12;              %// width of bar in legend. Normalized units

%// Plot errobar
h_er = errorbar([1 2], [2 3], [0.1 0.2], [color_spec linestyle_spec marker_spec]); 

%// Add dummy line for legend (as per Jens Boldsen) and create legend
hold on;
plot(0,0,color_spec); %// linestyle is always solid with no marker
h_le = legend('Mean','Standard deviation','Location','north');

%// Add short lines at each end of line in the legend
c_le = get(h_le, 'Children');                                                %// step 1
h_li = findobj(c_le, 'linestyle','-', 'color',color_spec, 'marker','none');  %// step 2
h_li = h_li(1); %// in case there's more than one
li_x = get(h_li,'XData');                                                    %// step 3
li_y = get(h_li,'YData');
line(li_x([1 1]), li_y+wid*[-.5 .5], 'parent',h_le, 'color',color_spec);     %// step 4
line(li_x([2 2]), li_y+wid*[-.5 .5], 'parent',h_le, 'color',color_spec);



案例II：R2014b，图例中的水平误差条

在Matlab R2014b中，图例不再是轴对象，也没有子对象。因此，必须针对案例I修改步骤1和2：

1. 创建图例时获取图例
2. 在这些图标中查找相应的行
3. 获取其x和y坐标
4. 利用这些坐标，在每一端创建两条短线。使这些线与初始线共享父线，以便它们与图例一起移动。

此外，此Matlab版本中的新语法有助于简化代码。

%// Define graph aspect
color_spec = 'r';       %// color of data and bars.
linestyle_spec = '--';  %// linestyle for data. The bars are always solid
marker_spec = 'o';      %// marker for data
wid = .12;              %// width of bar in legend. Normalized units

%// Plot errobar
h_er = errorbar([1 2], [2 3], [0.1 0.2], [color_spec linestyle_spec marker_spec]); 

%// Add dummy line for legend (as per Jens Boldsen)
hold on;
plot(0,0,color_spec); %// linestyle is always solid with no marker

%// Create legend and add short lines at each end of line in the legend
[~, icons] = legend('Mean','Standard deviation','Location','north');           %// 1
li = findobj(icons, 'type','line', 'linestyle','-');                           %// 2
li = li(1); %// in case there's more than one
li_x = li.XData;                                                               %// 3
li_y = li.YData;
line(li_x([1 1]), li_y+wid*[-.5 .5], 'parent',li.Parent, 'color',color_spec);  %// 4
line(li_x([2 2]), li_y+wid*[-.5 .5], 'parent',li.Parent, 'color',color_spec);



案例III：Pre-R2014b，图例中的垂直错误栏

这与案例I类似，但是有些人会对这些线条进行调整。 x 和 y 坐标是必需的。此外，还引入了一个新参数来控制图例中错误栏的长度。

%// Define graph aspect
color_spec = 'r';       %// color of data and bars.
linestyle_spec = '--';  %// linestyle for data. The bars are always solid
marker_spec = 'o';      %// marker for data
wid = .04;              %// width of bar in legend. Normalized units
len = .45;              %// length of main bar in legend. Normalized units

%// Plot errobar
h_er = errorbar([1 2], [2 3], [0.1 0.2], [color_spec linestyle_spec marker_spec]); 

%// Add dummy line for legend (as per Jens Boldsen) and create legend
hold on;
plot(0,0,color_spec); %// linestyle is always solid with no marker
h_le = legend('Mean','Standard deviation','Location','north');

%// Add short lines at each end of line in the legend
c_le = get(h_le, 'Children');    
h_li = findobj(c_le, 'linestyle','-', 'color',color_spec, 'marker','none');
h_li = h_li(1); %// in case there's more than one
set(h_li,'XData', repmat(mean(get(h_li,'XData')),1,2));
set(h_li,'YData', mean(get(h_li,'YData'))+len*[-.5 .5]);
li_x = get(h_li,'XData');
li_y = get(h_li,'YData');
line(li_x+wid*[-.5 .5], li_y([1 1]), 'parent',h_le, 'color',color_spec);
line(li_x+wid*[-.5 .5], li_y([2 2]), 'parent',h_le, 'color',color_spec);



案例IV：R2014b，图例中的垂直错误栏

同样，这与案例II类似，但有一些摆弄线条＆＃39;坐标。

%// Define graph aspect
color_spec = 'r';       %// color of data and bars.
linestyle_spec = '--';  %// linestyle for data. The bars are always solid
marker_spec = 'o';      %// marker for data
wid = .05;              %// width of small bars in legend. Normalized units
len = .45;              %// length of main bar in legend. Normalized units

%// Plot errobar
h_er = errorbar([1 2], [2 3], [0.1 0.2], [color_spec linestyle_spec marker_spec]); 

%// Add dummy line for legend (as per Jens Boldsen)
hold on;
plot(0,0,color_spec); %// linestyle is always solid with no marker

%// Create legend, modify line and add short lines
[~, icons] = legend('Mean','Standard deviation','Location','north');             
li = findobj(icons, 'type','line', 'linestyle','-');
li = li(1); %// in case there's more than one
li.XData = repmat(mean(li.XData),1,2);                                           
li.YData = mean(li.YData)+len*[-.5 .5];
li_x = li.XData;
li_y = li.YData;
line(li_x+wid*[-.5 .5], li_y([1 1]), 'parent',li.Parent, 'color',color_spec);
line(li_x+wid*[-.5 .5], li_y([2 2]), 'parent',li.Parent, 'color',color_spec);