如何将N-D数组的最后两个维度作为二维数组?

I have a 3D array in MATLAB, with size(myArray) = [100 100 50]. Now, I'd like to get a specific layer, specified by an index in the first dimension, in the form of a 2D matrix. I tried myMatrix = myArray(myIndex,:,:);, but that gives me a 3D array with size(myMatrix) = [1 100 50].

我在MATLAB中有一个3D数组，有size(myArray) =[100 100 50]。现在，我想要得到一个特定的层，由一维中的索引指定，以二维矩阵的形式。我尝试了myMatrix = myArray(myIndex，:，:);，但这给了我一个size(myMatrix) =[110050]的3D数组。

How do I tell MATLAB that I'm not interested in the first dimension (since there's only one layer), so it can simplify the matrix?

我如何告诉MATLAB我对第一维不感兴趣(因为只有一层)，这样它可以简化矩阵?

Note: I will need to do this with the second index also, rendering size(myMatrix) = [100 1 50] instead of the desired [100 50]. A solution should be applicable to both cases, and preferably to the third dimension as well.

注意:我还需要对第二个索引执行此操作，即呈现大小(myMatrix) =[100150]，而不是期望的[10050]。解决方案应该适用于这两种情况，最好也适用于第三维。

3 个解决方案

#1

Use the squeeze function, which removes singleton dimensions.

使用挤压函数，它删除单元素维度。

Example:

例子:

A=randn(4,50,100);
B=squeeze(A(1,:,:));
size(B)

ans =

    50   100

This is generalized and you needn't worry about which dimension you're indexing along. All singleton dimensions are squeezed out.

这是泛化的，您不必担心正在索引的维度。所有的单例维度都被挤出。

#2

reshape(myArray(myIndex,:,:),[100,50])

#3

squeeze, reshape and permute are probably the three most important functions when dealing with N-D matrices. Just to have an example how to use the third function:

在处理N-D矩阵时，挤压、重塑和排列可能是最重要的三个函数。举个例子，如何使用第三个函数:

A=randn(4,50,100);
B=permute(A(1,:,:),[2,3,1])

#1