Reassigning vector values using nested for-loops in matlab?

Question

In matlab I have two vectors, ind and ind3. ind = [1 2 3 4 5] and I want to define ind3 based on ind such that I want ind(3), ind(4) and ind(5) to be ind3(1) and ind3(2) and ind3(3). so that ind3 = [ind(3) ind(4) ind(5)] but for some reason I can't do this. I thought it would be simple to do using nested for loops but it doesn't really work.

for i=3:5
  for n=1:3
    ind3(n,:) = ind(i,:);
  end 
end

By going through the for-loops logically I know why the output is wrong.. but I don't get how else to do it? Am I being stupid and missing something really simple?!

I know its probably a simple answer but can anybody help??

Thanks.

so please make the question a bit more clear, do you want to copy, or shift by 2 columns ? — bla
– bla, Commented Feb 21, 2015 at 1:28
@bla no I misunderstood your solution... Its 1.30am and I just misread what you had written.. sorry!! deleted that comment. — Maheen Siddiqui
– Maheen Siddiqui, Commented Feb 21, 2015 at 1:30

user1543042 · Accepted Answer · 2015-02-21 01:27:10Z

1

If you want ind3 = [ind(3) ind(4) ind(5)] and you want to do it in a loop you just need a single loop. Additionally, since you're dealing with vectors you just have one indexing variable.

for n=1:3
  ind3(n) = ind(n + 2);
end

answered Feb 21, 2015 at 1:27

user1543042

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1 Comment

Maheen Siddiqui Over a year ago

... Thanks... I don't know why it didn't occur to me. Thanks.

rmccabe3701 · Accepted Answer · 2015-02-21 01:26:56Z

0

Maybe I'm misunderstanding your question but is this what u want:

ind3=ind(3:5)

answered Feb 21, 2015 at 1:26

rmccabe3701

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Comments

Mikhail Genkin · Accepted Answer · 2015-02-21 01:30:17Z

0

First of all, you said that your arrays are one dimensional (they are not matrices), and in your code by calling ind3(n,:) or ind(i,:) you treat them like 2 dimensional arrays.

As long as everything is 1 dimensional here, you need just one for loop:

for i=3:5
    ind3(i)=ind(i-2);
end

Explanation: here i=3,4,5. For i=3 you assign ind3[3]=ind[1], for i=4: ind3[4]=ind[2], for i=5: ind3[5]=ind[3].

Or you can simply call ind3=ind(3:5)

answered Feb 21, 2015 at 1:30

Mikhail Genkin

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