Turning array values into values on an x axis

Suppose I had a double array and the values were 2,3,6 and 9.

How would I create a double array where all of the values are 1, except the 2nd, 3rd, 6th and 9th, which are 2?

[Daniel Shub]

You link to double seems broken.

What have you tried so far?

[Matt Fig]

Tom's question

Suppose I had a double array and the values were 2,3,6 and 9.

How would I create a double array where all of the values are 1, except the 2nd, 3rd, 6th and 9th, which are 2?

Answer 1

[Wayne King]

   x = ones(500,1);
   indices = [2 3 6 9];
   x(indices) = 2;

Or

   x = ones(500,1);
   x(indices) = x(indices)+1;

[Tom]

That's great thanks.

What about if the indices is a vector (<1x4 double>) and not an array?

[Daniel Shub]

Ummm, it is 1x4 in Wayne's answer. It works if you make it 4x1.

[Tom]

Thanks - I got there in the end - I had to round my indices for some reason. Even though some of them had .0000 after it still wouldn't work until those had been removed.

Many thanks Wayne and Daniel.