Data gap finding in a time series

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Binu on 20 Apr 2020
Edited: Adam Danz on 23 Feb 2024
The attached file has two columns, time and levels. It has 6 missing data gaps. I want to find the index of each gap like this;
gap1 index 7-13
gap2 index 38-42
gap3 index 67-81
gap4 index 108-111
gap5 index 141-151
gap6 index 182-184
Your help is highly appreciated.
Thank you

Accepted Answer

Adam Danz
Adam Danz on 20 Apr 2020
Compute start and stop indices for NaN segments in height variable (column vector).
nanStartIdx = find(diff(isnan([0;height;0]))==1);
nanStopIdx = find(diff(isnan([0;height;0]))==-1);
Show the results.
% Show index of NaN values
ax = cla();
plot(isnan(height), '-k', 'LineWidth', 2)
ylim([-.2, 1.5])
ylabel('is NaN')
set(ax, 'YTick', [0,1], 'YTickLabel', {'False', 'True'})
hold on
arrayfun(@(start)xline(start, 'b-','Start'), nanStartIdx)
arrayfun(@(stop)xline(stop, 'c-','Stop'), nanStopIdx)
Binu on 21 Apr 2020
Thanks Adam. Much appreciated
Maria Battle
Maria Battle on 23 Feb 2024
Edited: Maria Battle on 23 Feb 2024
Good solution! If you wanted Stop to be aligned with the last NaN value of each gap, try
nanStopIdx = find(diff(isnan([0;height;0]))==-1)-1;

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