Counting a groupe of zeros

Hello,

I am trying to count a group of zeros with a for loop.

But it keeps giving me the error Index must be a positive integer or logical.

Stops=0;
for i=1:size(TachographVehicleSpeed)
if (TachographvehicleSpeed(i)==0&&TachographvehicleSpeed(i-1)~=0)
Stops = Stops + 1;
end
end

[Azzi Abdelmalek]

Give an example

Answer 1

[Image Analyst]

If you want to count groups of zeros, like the number of groups and number of zeros in each group, you can use regionprops() if you have the Image Processing Toolbox.

m = [1 0 0 0 1 1 0 0 1 0 0 0 0]; % Sample data
[labeledArray, numberOfZeroGroups] = bwlabel(m == 0);
stats = regionprops(labeledArray, 'Area');
zerosInEachGroup = [stats.Area]

Results:

numberOfZeroGroups = 3
zerosInEachGroup =
     3     2     4

[Nick van der maat]

Thanks ! this works just fine!

[Image Analyst]

You're welcome. If this answers your question best, then maybe you can officially "Accept" the answer and/or vote for it.

Answer 2

[Hooman Habibi]

The index starts from zero so you must start the loop from i=2. you can also count the consecutive zeros in row vector z by the following one liner

numberOfZerosInZ=sum(abs([z 1])+abs([1 z])==0)