Matlab中非均匀的imagesc（）轴 [英] Non-uniform axis of imagesc() in Matlab

问题描述

问题：是否可以在非均匀轴上说明图像？

Question: is it possible to illustrate an image on non-uniform axis?

详细信息：

我需要将多维时间序列说明为图像。但是这个时间序列的时间网格是非常不均匀的。这是一个例子：

I need to illustrate a multidimensional timeseries as an image. But the time grid of this timeseries is very non-uniform. Here is an example:

m = 10;
n = 3;
t = sort(rand(m, 1));  % non-uniform time
values = randn(m, n);  % some random values

数字，图（t，值）; 处理得很好。

但 imagesc（）将 t 转换为统一时间在 t（1）和 t（结束）之间根据文件：

But imagesc() converts t into uniform time between t(1) and t(end) according to documentation:

imagesc（x，y，C）将C显示为图像，并使用向量x和y指定
x和y轴的边界。

imagesc(x,y,C) displays C as an image and specifies the bounds of the x- and y-axis with vectors x and y.

因此，命令：

figure, imagesc(t, 1 : n, values'); colorbar;

说明统一时间网格上的图像。

illustrates the image on uniform time grid.

编辑：可以重新对时间序列进行重新采样统一分辨率。但我的时间序列已经很大了。

It's possible to re-sample the timeseries with higher uniform resolution. But my timeseries is already very large.

推荐答案

解决方案

尝试使用 surface 表示非均匀间距。

Try using surface for non-uniform spacing.

首先，创建一个与输入数据大小相同的3D xyz曲面：

First, create a 3D xyz surface of the same size as your input data:

m = 10;
n = 3;
t = sort(rand(m, 1));  % non-uniform time
values = randn(m, n);  % some random values
x = repmat(t,1,n);
y = repmat(1:n,m,1);
z = zeros(size(y));

然后，对您的值进行颜色映射。有一个很好的工具发布到mathworks文件交换， real2rgb ，这可以为你做到这一点：

Then, colormap your values. There is a nice tool posted to the mathworks file exchange, real2rgb, that can do this for you:

cdata = real2rgb(values);  % Where size(cdata) = [m n 3]

最后，绘制曲面。你甚至可以设置透明度。

Lastly, plot the surface. You can even get fancy and set the transparency.

surface(x,y,z,cdata,'EdgeColor','none','FaceColor','texturemap',...
  'CDataMapping','direct');
alpha(0.3)

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