number of times consecutive values occur

I have a row vector (1000 x 1) containing the values of 0 and nonzero values. I would like to find the number of times non-zero value occurs consecutively but with conditions - 2 consecutive of non-zero, 3 consecutive of non-zero, 4 consecutive of non-zero and so on (probably up to 100).

So for example I have X = [ 1 1 1 1 0 1 1 0 1 1 0 1 1 0 0 1 1 1]. The number of times 1 occurs 2-consecutively is 3. The number of times 1 occurs 3-consecutively is 1. The number of times 1 occurs 4-consecutively is 1.

I'm not sure how to tackle this.

Answer 1

[Stephen23]

Using basic MATLAB commands:

>> X = [ 1 1 1 1 0 1 1 0 1 1 0 1 1 0 0 1 1 1];
>> D = diff([0,X,0]);
>> V = find(D<0)-find(D>0);
>> U = unique(V) % lengths
U =
     2     3     4
>> histc(V,U) % number of occurrences
ans =
     3     1     1

[NMans]

Thanks! This works!

Answer 2

[Jan]

With FEX: RunLength:

X         = [1 1 1 1 0 1 1 0 1 1 0 1 1 0 0 1 1 1];
[B, N]    = RunLength(X);
N(B == 0) = [];  % Ignore the zeros
[R, Edge] = histcounts(N, 'BinMethod', 'Integers')

Or with a 2nd RunLength:

[B, N] = RunLength(X);
[V, R] = RunLength(sort(N(B ~= 0)))

Now the V(i) repetitions occurs R(i) times.

If you do not have a C-compiler installed, use RunLength_M from this submission instead.

[NMans]

Hi Jan,

Thanks for this. Sorry for the stupid question, I'm a newbie and i can't find any instruction online. I don't think I have any C-compiler installed so how do I use the function RunLength_M from the script you've written?

[Jan]

@NMans: See the example above. Replace "RunLength" by "RunLength_M".

[NMans]

Thanks!