MATLAB中没有for循环的多个数组的交集 [英] Intersection of multiple arrays without for loop in MATLAB

问题描述

我一直被告知，在MATLAB中可以省略几乎所有的for循环，并且它们通常会减慢该过程.那么这里有办法吗?:

I've always been told that almost all for loops can be omitted in MATLAB and that they in general slow down the process. So is there a way to do so here?:

我有一个单元格数组(tsCell). tsCell存储长度可变的时间数组.我想为所有时间数组(InterSection)找到一个相交的时间数组:

I have a cell-array (tsCell). tsCell stores time-arrays with varying length. I want to find an intersecting time-array for all time-arrays (InterSection):

InterSection = tsCell{1}.time
for i = 2:length{tsCell};
    InterSection = intersect(InterSection,tsCell{i}.time);
end

推荐答案

这是使用 accumarray ，假设在输入像元数组的每个像元中没有重复-

Here's a vectorized approach using unique and accumarray, assuming there are no duplicates within each cell of the input cell array -

[~,~,idx] = unique([tsCell_time{:}],'stable')
out = tsCell_time{1}(accumarray(idx,1) == length(tsCell_time))

样品运行-

>> tsCell_time = {[1 6 4 5],[4 7 1],[1 4 3],[4 3 1 7]};

>> InterSection = tsCell_time{1};
for i = 2:length(tsCell_time)
    InterSection = intersect(InterSection,tsCell_time{i});
end
>> InterSection
InterSection =
     1     4

>> [~,~,idx] = unique([tsCell_time{:}],'stable');
out = tsCell_time{1}(accumarray(idx,1) == length(tsCell_time));
>> out
out =
     1     4

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