How to count elements in array until criteria is met and output number of elements?

I have an array documenting states of a system and need to find system active duration.

An array looks something like

[1 1 1 1 2 2 2 3 3 3 3 3 3 3 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 5 5 5 5 1 1 1 2 2 3 3 3 3 4 4 4 4 4 4 4 4 4 4 4 4 5 5 5]

Each integer is the system state output from the controller. How can I create a method to count the number of elements in the array until the array becomes 5 (shutdown), repeat counting for the next system cycle, and output the duration (number of elements) of each cycle independently?

Answer 1

[Image Analyst]

Try using regionprops(), if you have the Image Processing Toolbox (type ver to check)

v = [1 1 1 1 2 2 2 3 3 3 3 3 3 3 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 5 5 5 5 1 1 1 2 2 3 3 3 3 4 4 4 4 4 4 4 4 4 4 4 4 5 5 5];
v5 = v == 5;
% Find starting locations and durations
props = regionprops(v5, 'PixelList', 'Area');

for k = 1 : length(props)
	startingLocations(k) = props(k).PixelList(1,1);
end
startingLocations % Echo to command window

startingLocations = 1×2

33 58

durations = [props.Area] % How many 5's are in each run of 5's.

durations = 1×2

4 3

[Nicholas Kavouris]

I do not have the image processing toolbox, and I would like to count the number of non 5 elements

[Image Analyst]

numberOfNon5elements = sum(v~=5)

Are you sure you don't have that toolbox? Most people do. Type ver to check.

[Nicholas Kavouris]

i do not, appreciate the help though

[Image Analyst]

Well that gets you the number of non-5 counts though.

By the way, take a look at splitapply(), groupsummary(), and findgroups(). They are handy functions to know about.

Answer 2

[Matt J]

Download this,

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

Then,

array = [1 1 1 1 2 2 2 3 3 3 3 3 3 3 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 5 5 5 5 1 1 1 2 2 3 3 3 3 4 4 4 4 4 4 4 4 4 4 4 4 5 5 5];

G=groupTrue(array~=5);

[~,~,durations]=groupLims(G,1)

durations =

32 21

[Nicholas Kavouris]

Can this function be used for multiple conditons? Also reading your examples does not include the groupLims fcn

[Matt J]

Can this function be used for multiple conditons?

You mean like this?

 G=groupTrue(array~=5 & array~=2);

The argument to groupTrue can be any logical vector.

Also reading your examples does not include the groupLims fcn

Now you have one!