Line selection if the temperature difference does not change?

Hello, I am using Matlab R2020b. I would like to ask how to find differences in column with temperature that have difference 0.0 or 0.01. I am reading data from .xls file, my code is this, but it doesnot look thats work well because sometimes when it is 0.01 it show 1 and sometimes 0:

difference = diff(TT.M01__C)

Adif = (abs(difference) <= 0.01)

Then I would like to ask if it is possible count that is number 1 in logical array is consecutively 15 times or more and say which row it start it. Because I need to find interval where the temperature doesnot change with that differences. I did this but I think it doesnot work properly because the problem above doesnot work good.

stps = 1:numel(Adif) % Step Counter

zv = stps(diff(Adif <= 0.01) > 0)

validRegions = zv(diff(zv) > 15)

Answer 1

[Adam Danz]

"sometimes when it is 0.01 it show 1 and sometimes 0"

This is likely due to round-off error. For example,

x = 0.01000001

x = 0.0100

x <= 0.01

ans = logical
   0

" count [the number of consecutive 1s] in logical array ... 15 times or more and [return the starting row]"

Adapt this answer: https://www.mathworks.com/matlabcentral/answers/604567-code-for-counting-and-lookup#answer_504877

[Sarlota Duskova]

Thank you for your quick help, I used round function to decimal so then my first question works. Then I adopted your answer for second problem so now is it perfect.

[Adam Danz]

Socially distant high-five! ✋

Answer 2

[Image Analyst]

To find out if you have stretches of 1's in Adif that are 15 or longer, you can use regionprops

Adif = [1, 0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 0, 0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 0, 0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 0, 1,1];
props = regionprops(logical(Adif), 'Area', 'PixelIdxList'); % Measure lengths of all runs of 1's.
allLengths = [props.Area] % Extract all the lengths into one double vector.
% Print out all runs where the length is 15 or more.
starts15 = [];
for k = 1 : length(allLengths) % For every region...
    if allLengths(k) >= 15 % If that region is 15 elements or longer...
        % Print it out to the command window.
        fprintf('Region %d is %d elements long and starts at index %d.\n', ...
			k, allLengths(k), props(k).PixelIdxList(1));
        % Save this index of this run
        starts15 = [starts15, props(k).PixelIdxList(1)];
    end
end

You'll see

allLengths =

1 15 18 17 2

Region 2 is 15 elements long and starts at index 3.

Region 3 is 18 elements long and starts at index 20.

Region 4 is 17 elements long and starts at index 40.