True false results to be saved as a value

I have a vector, a = [1,0,1,1,1,0,0,0......]

I want to say that when a is true, or when the elements in a are equal 1, to make another vector correspond.

So if I wanted the true elements to correspond as .25, how can I make another vector that reads: b = [.25,0,.25,.25,.25,0,0,0.....,]?

I was thinking something along the lines below.

a = zeros(1,10)
b = zeros(size(a))
while a == 1
     b = .25
end

Answer 1

[Stephen23]

Simplest would be to just multiply the logical vector by 0.25:

>> a = [1,0,1,1,1,0,0,0];
>> b = a*0.25
b =
 0.25   0   0.25   0.25   0.25   0   0   0

A more complex but versatile solution would be to convert the logical values into linear indices:

>> c = [0,0.25];
>> c(a+1)
ans =
   0.25   0   0.25   0.25   0.25   0   0   0

[Dylan Mecca]

Is there a way to solve it the way I asked? Your answer doesn't do that.

[Stephen23]

If you want to use a loop then you will need to use indexing:

a = [1,0,1,1,1,0,0,0];
b = zeros(size(a));
for k = find(a)
    b(k) = .25;
end

or

b = zeros(size(a));
for k = 1:numel(a)
    if a(k)
        b(k) = .25;
    end
end

[Jan]

@Dylan: The while approach does not work. See the documentation:

doc while

while creates a loop until the scalar condition gets false. But a==1 is 1. a vector and 2. a loop does not branch to different commands, such that your problem is not a job for a loop at all. In consequence while is a wrong approach and that Stephen suggests something completely different is the right idea.

A method using a loop would be:

a = [1,0,1,1,1,0,0,0];
b = zeros(size(a));
for k = 1:numel(a)
  if a(k)
    b(k) = 0.25;
  end
end

But Stephen's suggestions are cleaner, easier and faster. +1