finding index of a function

Question

shobhit mehrotra 2015-1-27

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/172094-finding-index-of-a-function

回答： Thomas Feja 2015-1-27

Hello, I have the following code, When the cell array is created it contains values of AA when the condition is meet. I want to also create a cell array of the index of AA, AA(n) n = 1:length AA.

AA = [ 1 2 3 5 7 10 9 11 13 14 17 19 17 22 25];

data = mat2cell(AA, 1, diff([0 find(diff(AA) < 0) numel(AA)]))

Thanks!

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shobhit mehrotra 2015-1-27

Im trying to create another data cell array with indices that meet the condition. dataind = [(1, 2, 3, 4, 5, 6), (7,8,9, 10, 11, 12), (13,14,15)]

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Answer 1

Thomas Feja 2015-1-27

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/172094-finding-index-of-a-function#answer_166050

在 MATLAB Online 中打开

If you want go for a single line solution, this will work:

data = arrayfun(@(x,y)x:y,[1,1+find(diff(AA)<0)],[find(diff(AA)<0),numel(AA)],'UniformOutput',false)

This is compact but hard to read. So you might prefer this solution:

idxNegDiff = [find(diff(AA)<0),numel(AA)];
start = 1;
for idx = 1:length(idxNegDiff)
   c{idx} = start:idxNegDiff(idx);
   start = idxNegDiff(idx)+1;
end

Either way you can verify the result using:

celldisp(c)