how to creat this vector?

hello everyone

I have vector

X=[1 0 0 1 1 0 1 1 1 1 0 0 0 1 1 0 1 1 1 1 1 0]

i need this transformation

if Nbr of 1 >3 the vector become:

Y=[0 0 0 0 0 0 1 1 1 1 0 0 0 0 0 0 1 1 1 1 1 0]

Answer 1

[Stephen23]

An easy solution using a loop:

>> X = [1,0,0,1,1,0,1,1,1,1,0,0,0,1,1,0,1,1,1,1,1,0]
X =
   1   0   0   1   1   0   1   1   1   1   0   0   0   1   1   0   1   1   1   1   1   0

D = diff([0,X,0]);
B = find(D>0);
E = find(D<0)-1;
N = 3;
for k = 1:numel(B)
    if (E(k)-B(k))<N
        X(B(k):E(k)) = 0;
    end
end

>> X
X =
   0   0   0   0   0   0   1   1   1   1   0   0   0   0   0   0   1   1   1   1   1   0

Answer 2

[Jan]

The question is not clear, but I assume you mean: set values to 0, if less than 3 neighboring elements are 1.

With FEX: RunLength:

X        = [1 0 0 1 1 0 1 1 1 1 0 0 0 1 1 0 1 1 1 1 1 0];
[B, N]   = RunLength(X);
B(N < 3) = 0;
Y        = RunLength(B, N);

If you do not have a compiler installed, use RunLength_M from the same submission.

Answer 3

[Torsten]

X=[1 0 0 1 1 0 1 1 1 1 0 0 0 1 1 0 1 1 1 1 1 0];
if sum(X)>3
  X=[0 0 0 0 0 0 1 1 1 1 0 0 0 0 0 0 1 1 1 1 1 0];
end