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SB
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Selecting cross values from two arrays

Asked by SB
on 13 Sep 2019
Latest activity Answered by Andrei Bobrov
on 17 Sep 2019
I have three arrays namely, s = [0,1000,2000], d = [0,1000,2000] and J = [0,5000,8000], where, J = 3*d+2000. Now within a for loop, when s(1) and d(1) are selected, I want to select J(1). When s(2),d(1) is selected, I want to select J(3). When s(2), d(2) is selected, I want to select J(2). What would be a generic way of doing this instead of hard coding?

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Raj
on 13 Sep 2019
Sorry but your question is not clear at all.
"when s(1) and d(1) are selected" - What do you mean by 'selected'? you want user to give selection inputs?
"I want to select J(1)" - You want J(1) to get computed here or you already have J matrix before 'for' loop and you want to select J(1) & do something with it?
Hi,
Can you explain what you want to do with these matrices, your doubt is not clear.

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2 Answers

Answer by KALYAN ACHARJYA on 17 Sep 2019
Edited by KALYAN ACHARJYA on 17 Sep 2019

Form the question, if you pattern the s,d, and J , it becomes
1 1 1
2 1 3
2 2 2
Have you find any pattern on the sequence? I dont think so...(one label condition)
Though you can do that by mutiple loops and condition statements, but direct implementation is much easier and faster here.
"What would be a generic way of doing this instead of hard coding?"
In addition, all vectors having 3 lengths only, you can do it by direct implementation, why do you think you have to go for "for loop" here.
Good Luck!

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Answer by Andrei Bobrov
on 17 Sep 2019

s = [0,1000,2000];
d = [0,1000,2000];
J = [0,5000,8000];
ii = fullfact([3,3,3]);
out = [s(ii(:,1))',d(ii(:,2))',J(ii(:,3))'];
or
[ii,jj,k] = ndgrid(s,d,J);
out = [ii(:),jj(:),k(:)];

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