Extracting the index numbers of greater than zero values of an array in different / separate sets MATLAB

I have an array of n length. Array has braking energy values. Index numbers represents Time in seconds.

Structure of array is as following:

1 to 140 index numbers array has zero values. (The time during which vehicle was not braking)

141 to 200 index numbers array has random energy values. (The time when vehicle was braking and regenerating energy)

201 to 325 index number array has zero values. (The time during which vehicle was not braking)

326 to 405 index numbers array has random energy values. (The time when vehicle was braking and regenerating energy)

and so on. This sequence goes on till nth number of array.

What I want to do is to get starting and ending index number of each set of energy values.

For example the result I must get shall be like

141 - 200

326 - 405

so on...

Latter this time will be used for charging of battery.

Can someone please suggest what method or technique shall I use to get this result.

[Image Analyst]

Please attach some data for us to work with. Make it easy for us to help you, not hard. This is trivially easy with regionprops() if you have the Image Processing Toolbox.

[Shahab Khan]

I have attached the vector i am working with.

Thanks

Answer 1

[Guillaume]

startends = find(diff([0, yourarray > 0, 0]));
startends = reshape(startends, 2, [])';
startends(:, 2) = startends(:, 2) - 1

[Shahab Khan]

Thanks for answering, your logic is correct but i am getting dificulty in applying it.

startends = find(diff([0, EnergyB' > 0, 0]));

% This command all the starting and ending index of positive values but the ending number is always 1 index greater. For example , it should get index 212 but it gets 213.

startends = startends(:, 2)';

% This command gives me ending index number +1. for example it should give me 212 but its getting 213 index number.

startends(:, 2) = startends(:, 2) - 1

% This command gives me error

Index in position 2 exceeds array bounds (must not exceed 1).

my EnergyB is Vertical vector.

Any help would be great.

Thanks

[Guillaume]

I have no idea what I was thinking when I wrote the second line. It's not what I intended at all.

Fixed now. You understood how the code works anyway, judging by your comments.

Note that if energyB is a column vector, then:

startends = find(diff([0; energyB > 0; 0])); 

will be more efficient than transposing. The rest would stay the same.

[Shahab Khan]

Great It works perfectly. Thanks for your help.

Answer 2

[madhan ravi]

Use logical indexing:

idx=find(values>0) %gives linear indices
values(values>0) %gives you all the values greater than zero