How to group logical numbers in a vector?

I am trying to count how many groups of ones in a vector. Number 1 repeated three times in three positions in this vector.

Vector = [1 1 1 0 0 0 0 1 1 1 1 1 0 0 0 0 0 1 1 1 1 1 1];

The expected answer is

Num_gr_1 = 3

Could you help please?

[Jeffrey Clark]

@Khaldon Qaid, Num_gr_1 = sum(Vector>[Vector(2:end) 0]);

[Khaldon Qaid]

Thank you for your help.

Answer 1

[Matt J]

Use this:

https://www.mathworks.com/matlabcentral/fileexchange/78008-tools-for-processing-consecutive-repetitions-in-vectors

Vector = logical( [1 1 1 0 0 0 0 1 1 1 1 1 0 0 0 0 0 1 1 1 1 1 1] );

Num_gr_1=max(groupTrue(Vector))

Num_gr_1 = 3

[Khaldon Qaid]

Thank you for your help.

Answer 2

[dpb]

>> num_gr_1=sum(diff(Vector)==1)+(Vector(1)==1)
num_gr_1 =
     3
>> 

There are FEX submissions for runlength encoding that will give you all the details besides just the number of groups asked for here...if you want/need the locations of the groups,

>> gr_1=find([0 diff(Vector)]==1)
gr_1 =
     1     8    18
>> 

Above is specific for [0, 1]; the FEX submissions will find any/all runs. The above logic will deal with any specific values by converting the input vector to logical based on the looked-for value, but that's the limit to its flexibility.

But, it's quick/simple for the specific task.

[Khaldon Qaid]

Thank you for your help.

Answer 3

[Image Analyst]

If you have the Image Processing Toolbox you can label each group and count them in a single line of code with bwlabel :

Vector = [1 1 1 0 0 0 0 1 1 1 1 1 0 0 0 0 0 1 1 1 1 1 1]; % Sample data
[L, Num_gr_1] = bwlabel(Vector) % Label groups and count groups.

L = 1×23

1 1 1 0 0 0 0 2 2 2 2 2 0 0 0 0 0 3 3 3 3 3 3

Num_gr_1 = 3

[Khaldon Qaid]

Thank you for your help.