# Get the numbers of rows where values change

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Maja Zdulska on 16 Jul 2020
Commented: Maja Zdulska on 16 Jul 2020
Hi,
I have an array of data, structured like this:
Latitude Longitude Height
23 54 7
23 54 3
23 54 8
23 55 4
23 55 2
24 54 0
24 54 1
24 55 2
24 55 7
How can I get the numbers of the rows where either Latitude or Longitude changes (so from the example above the output would be rows 3, 5 and 7)?
##### 2 CommentsShowHide 1 older comment
Maja Zdulska on 16 Jul 2020
Yes, sorry, you're absolutely correct.

Image Analyst on 16 Jul 2020
By the time you get down to row 3, nothing has changed yet. Row 3 is still the same as rows 1 and 2. Don't you mean 4, 6, and 8? Those are the actual rows where a change is first encountered.
Try this:
m = [
23 54 7
23 54 3
23 54 8
23 55 4
23 55 2
24 54 0
24 54 1
24 55 2
24 55 7]
latChanged = [0; diff(m(:, 1))] % Logical -- use find() if you want row numbers.
lonChanged = [0; diff(m(:, 2))] % Logical -- use find() if you want row numbers.
eitherChanged = find(latChanged | lonChanged) % Row numbers where either lat OR lon changed.
Maja Zdulska on 16 Jul 2020
Many thanks.

David Hill on 16 Jul 2020
c=find(b(:,1)~=0|b(:,2)~=0);%c=3,5,7

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