matlab - 按指定顺序创建 1 的数组

Question

我有一个位置矩阵:

positionMatrix = [1 2 3; 1 3 2; 2 1 3];

我想要一个简单的实现(没有 for 循环)，它会生成如下数组:

% there are 3 lines in positionMatrix, so it should generates 3 arrays of ones
array 1 should be [1 0 0; 0 1 0; 0 0 1] %from positionMatrix 1 2 3 
array 2 should be [1 0 0; 0 0 1; 0 1 0] %from positionMatrix 1 3 2
array 3 should be [0 1 0; 1 0 0; 0 0 1] %from positionMatrix 2 1 3

positionMatrix 可以是 M x N(M 不等于 N)。

Answer 1

将输出生成为单个 3D 数组

 [M N] = size( positionMatrix );
 mx = max(positionMatrix(:)); % max column index
 out = zeros( [N mx M] );
 out( sub2ind( size(out), ...
         repmat( 1:N, [M 1] ),...
         positionMatrix, ...
         repmat( (1:M)', [1 N] ) ) ) = 1;
out(:,:,1) =
 1     0     0
 0     1     0
 0     0     1
out(:,:,2) =
 1     0     0
 0     0     1
 0     1     0
out(:,:,3) =
 0     1     0
 1     0     0
 0     0     1

如果您希望每个输出矩阵作为不同的单元格，您可以使用mat2cell

>> mat2cell( out, N, mx, ones(1,M) )