Question

我有一个矩阵，其矩阵随机分布在整个矩阵中。我想要连续值的索引，而且，我想要一个与原始矩阵大小相同的矩阵，其中连续值的数量存储在连续值的索引中。例如

  original_matrix = [1 1 1;2 2 3; 1 2 3];

  output_matrix = [3 3 3;2 2 0;0 0 0];

我一直在努力寻找解决这个问题的方法。它与气象数据质量控制有关。例如，如果我有一个来自多个传感器的温度数据矩阵，并且我想知道哪些天具有恒定的连续值，以及多少天是恒定的，那么我可以将数据标记为可能有故障。

温度矩阵是天数x站数，我想要一个输出矩阵，它也是天数x站数，其中连续值如上所述被标记。

如果您有解决方案，请提供！谢谢。

Answer 1

对于这类问题，我创建了自己的效用函数runlength：

function RL = runlength(M)
% calculates length of runs of consecutive equal items along columns of M

% work along columns, so that you can use linear indexing

% find locations where items change along column
jumps = diff(M) ~= 0;

% add implicit jumps at start and end
ncol = size(jumps, 2);
jumps = [true(1, ncol); jumps; true(1, ncol)]; 

% find linear indices of starts and stops of runs
ijump = find(jumps);
nrow = size(jumps, 1);
istart = ijump(rem(ijump, nrow) ~= 0); % remove fake starts in last row
istop = ijump(rem(ijump, nrow) ~= 1); % remove fake stops in first row
rl = istop - istart;
assert(sum(rl) == numel(M))

% make matrix of 'derivative' of runlength
% don't need last row, but needs same size as jumps for indices to be valid
dRL = zeros(size(jumps)); 
dRL(istart) = rl;
dRL(istop) = dRL(istop) - rl;

% remove last row and 'integrate' to get runlength
RL = cumsum(dRL(1:end-1,:));

它仅适用于列，因为它使用linear indexing。由于你想在行上做类似的事情，你需要来回移调，所以你可以像你这样使用它：

>> original = [1 1 1;2 2 3; 1 2 3];
>> original = original.';  % transpose, since runlength works along columns
>> output = runlength(original);
>> output = output.';  % transpose back
>> output(output == 1) = 0;  % see hitzg's comment
>> output

output =

     3     3     3
     2     2     0
     0     0     0

矩阵中常量连续值的指数，以及常数的数量

1 个答案: