循环检查数组中每个元素的重复次数 - 在 while 期间卡住

Question

假设我有以下数组，

x = [1, 2, 3, 4, 5, 5, 6, 1, 1];

我正在尝试编写一个循环遍历每个元素并检查是否有重复的函数。例如，"does x(1) == x(2) OR does x(1) == x(3) OR ... does x(1) == x(9)"。到目前为止我有以下代码：

N = length(x);    
sharedPosition = zeros(1, N);

for i = 1:N    
    for j = 1:N
        indexSum = i + j;    
        while indexSum <= N    
            isShared = x(1, i) == x(1, i+j);    
            sharedPosition(1, i) = sum(isShared);    
        end    
    end    
end

然而，代码似乎从未通过第一次迭代，并且在 "Busy" 中闲置。如何更好地实现这段代码？

Answer 1

您的问题是因为您从未在 while 内更改 indexSum 或 N，因此循环条件始终为真！

你可以不用 while 而只用一个 for

% size and numel are usually preferred over length, as it's ambiguous which dimension
% you are getting the "length" of.
N = numel(x); 
sharedPosition = zeros(1, N);

% Loop over values
for ii = 1:N
    % Store the number of times the given value occurs
    % MATLAB can compare a scalar to an entire array, no need to loop again.
    sharedPosition(ii) = sum(x(ii) == x);
end

循环检查数组中每个元素的重复次数 - 在 while 期间卡住

Looping to check for number of repeats of each element in array - stuck during while

arrays

matlab

unique