Identify when a exceedance occurs and return the start point and length of each exceedance

I have two large arrays with magnetic heading values:

hdg1=[10;10;10;10;10;10;10;10;10;10;10;10]; %actual data is thousands of values.

hdg2=[12;18;18;18;13;14;10;20;20;12;13;12];

calculate delta between each item.

hdgdelta = abs(hdg1 - hdg2);

Need help with:

Identifying when and how long hdgdelta values are greater than say 6.

I would like to see the results returned as such:

Array1: The starting points/rows where hdgdelta exceedance groups exceed the value of 6. (Rows 2 and 8 in this case).

Array2: The duration of those splits. i.e The duration/count for when subsequent rows have a value greater than 6. Ie. 2,3,4, (length of 3) and 8,9 (length of 2)

The example result that I would like to see:

Array1 = [2;8]; %starting points/rows where exceedance happen

Array2 = [3;2]; %duration (in # of rows) for each exceedance.

Answer 1

[Voss]

One way is to use strfind to find the starts and ends of the sections where hdgdelta>=6:

hdg1=[10;10;10;10;10;10;10;10;10;10;10;10];  %actual data is thousands of values.
hdg2=[12;18;18;18;13;14;10;20;20;12;13;12];

hdgdelta = abs(hdg1 - hdg2);

idx = hdgdelta(:).' >= 6

idx = 1x12 logical array
   0   1   1   1   0   0   0   1   1   0   0   0

start_idx = strfind([false,idx],[false,true])

start_idx = 1x2

2 8

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end_idx = strfind([idx,false],[true,false])

end_idx = 1x2

4 9

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Array1 = start_idx(:);
Array2 = end_idx(:)-start_idx(:)+1;

disp(Array1)

     2
     8

disp(Array2)

     3
     2