How can I remove a value from an array but keeping an empty slot

By running the following code I am able to remove the number '2'.

a = [1;2;3];
a(2) = [];
a = [1;3];

But I want my answer to be something like this.

a = [1;[];3];

The reason for this is due to I don't want to reduce the size of the array. How can this be achieved?

Answer 1

[Stephen23]

Method One: replace with NaN (best solution):

 a = [1;2;3];
 a(2) = NaN;

Method Two: store a mask:

 a = [1;2;3]
 mask = true(size(a));
 mask(2) = false;

Method Three: use a cell array:

 a = {1;2;3};
 a{2} = [];

Personally I would use either one or two: they do not require moving the data in memory. Any method that actually changes the size of the array will require the array to be copied when it is changed, which is slow and unnecessary.

[Daniel Eidsvåg]

I was looking into option three, but as you say it's slow and unnecessary. Method one works just fine! Thank you!