How to replace a certain value for another one once in a vector without using the index?

Question

Eduardo Alfaro 2017-2-5

编辑： Sebastian 2017-2-5

vec = [89.7000 9.1000 68.0000 87.7000 91.7000 9.1000]
rep = 50

I have to replace one of the 9.1000s in vec for rep without using indices.

Star Strider 2017-2-5

I have to replace one of the 9.1000s in vec for rep without using indices.

That does not seem possible to me. I cannot imagine a way to address the elements of a vector without using some sort of indexing.

Answer 1

Sebastian 2017-2-5

编辑：Sebastian 2017-2-5

Use this to replace all elements with the value of 9.1 with rep:

vec(vec == 9.1) = rep
vec =
   89.7000   50.0000   68.0000   87.7000   91.7000   50.0000

Alternatively use this to find the indices of the elements and then replace them:

ind = find(vec == 9.1)
ind =
     2     6
vec(ind) = rep
vec =
     89.7000   50.0000   68.0000   87.7000   91.7000   50.0000

If you only want to replace the first element, use this:

vec(find(vec == 9.1, 1)) = rep
vec =
     89.7000   50.0000   68.0000   87.7000   91.7000    9.1000

Star Strider 2017-2-5

That is implied indexing, since find returns the index.

Sebastian 2017-2-5

编辑：Sebastian 2017-2-5

I know but I think there is no way around find if you want to replace only certain elements and not all of them.