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True false results to be saved as a value

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Dylan Mecca
Dylan Mecca on 22 Feb 2018
Edited: Stephen on 22 Feb 2018
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

Accepted Answer

Stephen on 22 Feb 2018
Edited: Stephen on 22 Feb 2018
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
Jan on 22 Feb 2018
@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;
But Stephen's suggestions are cleaner, easier and faster. +1

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