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How to insert an element after each number in a vector?

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Dear all,
I would like to add an element after each value in a vector, for example:
a=[10,2,40,58,100,90,40,30,4];
I would like to add 1 to vector values:
result = [1,10,1,2,1,40,1,58,1,100,1,90,1,40,1,30,1,4,1];
Help me please.....
  1 Comment
Image Analyst
Image Analyst on 5 May 2019
Instead of "after each number" don't you mean "after each number, EXCEPT the first number, where the number is also before the first number?" That's what Star and Adams solutions do. Or do you really mean what you said, instead of the "result" you gave, and so there would be no 1 at the beginning?

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Accepted Answer

Star Strider
Star Strider on 5 May 2019
One approach:
a=[10,2,40,58,100,90,40,30,4];
result = [ones(size(a)); a];
result = [result(:); 1]'
producing:
result =
1 10 1 2 1 40 1 58 1 100 1 90 1 40 1 30 1 4 1
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More Answers (2)

Adam Danz
Adam Danz on 5 May 2019
result = [reshape([ones(size(a));a],length(a)*2,1);1]';

Image Analyst
Image Analyst on 5 May 2019
Instead of "after each number" did you mean "after each number, EXCEPT the first number, where the number is also before the first number?" That's what Star and Adam's solutions do. Or do you really mean what you said, instead of the "result" you gave, and so there would be no 1 at the beginning?
Just to be complete and cover all ambiguities, I'll give the other solution. If you really want what you said in words, rather than the numerical result you gave, then use this code:
result = [a; ones(size(a))]
result = result(:)'
The result is:
result =
10 1 2 1 40 1 58 1 100 1 90 1 40 1 30 1 4 1
Note: 1's are only after the numbers and not before the first one.
  1 Comment
laith Farhan
laith Farhan on 5 May 2019
Thanks Image Analyst, yes, it might help me for another cases.

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