matlab fill legend

To add a legend to a filled area plot in MATLAB, you can use the `legend` function after creating the plot. Here's an example:

x = 0:pi/100:2*pi;
y1 = sin(x);
y2 = cos(x);

fill([x fliplr(x)], [y1 fliplr(y2)], 'r');
hold on;
plot(x, y1, 'b');
plot(x, y2, 'g');

legend('Filled area', 'Sine', 'Cosine');

This code will create a filled area plot with a red color, and then add two sine and cosine plots on top of it. The `legend` function is then used to add a legend to the plot with labels for each of the three plots. You can customize the legend further using additional arguments to the `legend` function.

相关问题

use fill but not legend

If you want to label the filled area itself without using a legend in MATLAB, you can use the `text` function to add a label directly to the plot. Here's an example:

x = 0:pi/100:2*pi;
y1 = sin(x);
y2 = cos(x);

fill([x fliplr(x)], [y1 fliplr(y2)], 'r');
text(mean(x), mean([y1, y2]), 'Filled area', 'HorizontalAlignment', 'center');

In this code, the `fill` function is used to create a filled area plot with a red color. Then, the `text` function is used to add the label "Filled area" to the center of the plot using the mean value of the `x` and `y` coordinates. The `'HorizontalAlignment', 'center'` argument is used to center the label horizontally. You can adjust the position and style of the label by adjusting the arguments to the `text` function.

生成一段用MATLAB绘制两条曲线之间的阴影图的程序代码，要求用fill函数实现

假设有两个函数y1和y2，代码如下：

x = 0:0.1:10; % 生成x轴数据
y1 = sin(x); % 生成y1数据
y2 = cos(x); % 生成y2数据

figure; % 创建新的绘图窗口
hold on; % 启用hold功能，即绘制多个图形
plot(x, y1, 'LineWidth', 2); % 绘制y1曲线
plot(x, y2, 'LineWidth', 2); % 绘制y2曲线

idx = y1 >= y2; % 找出y1大于等于y2的索引
fill([x(idx), fliplr(x(idx))], [y1(idx), fliplr(y2(idx))], [0.9 0.9 0.9], 'EdgeColor', 'none'); % 绘制阴影部分

legend('y1', 'y2', 'y1 >= y2'); % 添加图例

解释一下代码：

1. 首先生成x轴数据和y1、y2数据。
2. 创建新的绘图窗口，并启用hold功能。
3. 绘制y1和y2曲线。
4. 找出y1大于等于y2的索引，即要绘制阴影部分的数据。
5. 使用fill函数绘制阴影部分，其中x的取值是idx为true的部分，y的取值是y1和y2中idx为true的部分，颜色为[0.9 0.9 0.9]，边框颜色为'none'。
6. 添加图例。

运行代码，可以得到如下图形：