Find the index of the first values in ascending array that are greater than each values from random array without for loop

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Jérémy 2018-3-26

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评论： Jérémy 2018-3-27

采纳的回答： Walter Roberson

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Hello,

I have a random vector A=rand(n,1) and a given vector B(n,1) which is sorted in ascending values. I want to find the index of the first value of A that is greater than each values of my random vector. For example with:

A = [1 ; 6 ; 2 ; 8 ; 3]; B = [2 ; 4 ; 6 ; 8 ;10];

It would give: indexes = [1 4 2 5 2].

My current solution consist of using a for loop:

ix = zeros(N,1);
for i = 1:N
   r = rand;
   ix(i) = find(B>A,1);
end

I would like to be able to do the same without using a for loop in order to increase the speed of the operation.

Thanks

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采纳的回答

Walter Roberson 2018-3-26

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https://ww2.mathworks.cn/matlabcentral/answers/390703-find-the-index-of-the-first-values-in-ascending-array-that-are-greater-than-each-values-from-random#answer_312002

Second output of either histc or histcounts

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Guillaume 2018-3-26

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Or just the first output of discretize

discretize(B, A)+1

Jérémy 2018-3-27

Works like a charm ! Thanks

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MATLAB Language Fundamentals Matrices and Arrays Creating and Concatenating Matrices

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