Question

我对MatLab很新，我有运行长度编码代码，但它似乎不起作用，你能帮助我吗？

我有这个输入：

ChainCode  = 11012321170701000700000700766666666666665555555544443344444333221322222322

我想把它变成RLE输出：

(1,2), (0,1), (1,1), (2,1), (3,1), (2,1), (1,2), (7,1), (0,1), (7,1), (0,1), 
(1,1), (0,3), (7,1), (0,5), (7,1), (0,2), (7,1), (6,13), (5,8), (4,4), (3,2), 
(4,5), (3,3), (2,2), (1,1), (3,1), (2,5), (3,1), (2,2)

这是我的代码：

lengthcode = 1;
N = 1;

for i = 2:length(ChainCode)

    if x(i)==x(i-1)
        N = N + 1; 
        valuecode(N)  = x(i);
        lengthcode(N) = lengthcode(N) + 1;
    else 
        N = 1;
        lengthcode = 1;
    end

    i = i + 1;

end

但这不起作用，我仍然对如何打印这样的输出感到困惑。

我希望你能帮助我。谢谢。

Answer 1

这是一个没有循环，cellfun或arrayfun的紧凑型解决方案：

chainCode = '11012321170701000700000700766666666666665555555544443344444333221322222322';
numCode = chainCode - '0'; % turn to numerical array

J=find(diff([numCode(1)-1, numCode]));
relMat=[numCode(J); diff([J, numel(numCode)+1])];

Answer 2

通过坚持原始实现，以下简单更改应该有效。

chainCode = '11012321170701000700000700766666666666665555555544443344444333221322222322';
numCode = chainCode - '0'; % turn to numerical array
relMat = [];
numCode = [numCode nan]; % dummy ending

N = 1;
for i = 1:length(numCode)-1   
    if numCode(i)==numCode(i+1)
        N = N + 1;
    else
        valuecode = numCode(i);
        lengthcode =  N;
        relMat = [relMat; valuecode lengthcode];
        N = 1;
    end
end

您可以根据需要格式化输出。例如，作为序列：

relMatT = relMat';
relSeq = relMatT(:)';

或将字符串格式化为建议的输出：

relString = [];
for i = 1:length(relMat)
    relString = [relString, sprintf('(%d, %d), ', relMat(i,1), relMat(i,2))];
end

作为扩展，如果你的源序列中有字母数字，你应该修改上面的内容，以便比较字符串而不是数字。

UPDATE ：要计算原始relMat中唯一代码对的出现次数，请尝试查找对，并按行计数零差异。例如：

relMatUnique = unique(relMat, 'rows'); % find unique pairs 
nPairs = length(relMatUnique);
nOccur = zeros(nPairs, 1);
for i = 1:nPairs
    pairInMat = bsxfun(@minus, relMat, relMatUnique(i,:)); % find pair in relMat
    nOccur(i) = sum(~sum(pairInMat, 2));
end
relMatOccur = [relMatUnique nOccur]; % unique pairs and number of occurrences

Answer 3

您可以避免使用for循环：

chainCode = '11012321170701000700000700766666666666665555555544443344444333221322222322';
numCode = chainCode - '0'; % turn to numerical array

% detect edges (changes)
edges = arrayfun( @(x,y) x ~= y,    ...
                  numCode(1:end-1), ...
                  numCode(2:end));
% get indexes
idx = find(edges);

% create tuples
relMat = cell2mat(arrayfun(         ...
  @(b,e) [ numCode(b) ; e-b+1 ],    ...
  [ 1 (idx + 1) ],                  ...
  [ idx length(numCode) ],          ...
  'UniformOutput', false));

Answer 4

% Convert string to numeric array
ChainCodeString  = '11012321170701000700000700766666666666665555555544443344444333221322222322';
ChainCodeArray = ChainCodeString - '0';

% Initialize
CurrentRleValue = ChainCodeArray(1);
CurrentRleCount = 1;
RleCodeIndex = 1;

for i = 2 : length(ChainCodeArray)
    if ChainCodeArray(i)==ChainCodeArray(i-1)
        % Increment current run-length count
        CurrentRleCount = CurrentRleCount + 1;
    else
        % Store current run-length
        valuecode(RleCodeIndex) = CurrentRleValue;
        lengthcode(RleCodeIndex) = CurrentRleCount;
        RleCodeIndex = RleCodeIndex + 1;

        % Initialize next run-length
        CurrentRleValue = ChainCodeArray(i);
        CurrentRleCount = 1;
    end;
end;

Matlab中的运行长度编码

4 个答案: