Call the most recent timetable value

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Poison Idea fan 2021-3-3

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https://ww2.mathworks.cn/matlabcentral/answers/762036-call-the-most-recent-timetable-value

回答： Poison Idea fan 2021-3-3

I have 2 timetables. In order to make a calculation on the data in the first table, I need to call the most recent values of the second table.

for k = 1:numel(rawData_Timetable)
    value(n,:) = reflectivity_Timetable.('Reflectivity')(most_recent) .* rawDataTT.('Spectra')(n,:);
end

How could I compare the times in the rawData_Timetable and find the most recent row of the reflectivity_Timetable for the calculation?

Initially I thought to loop through the reflectivity_Timetable and concatenate to a new timetable, but I feel there must be asolution that doesn't involve creating a nested loop through the rawData_Timetable and reflectivity_Timetable.

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Answer 1

Poison Idea fan 2021-3-3

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So, I answered my own question. But, maybe someone has a better solution!

I take the difference between the times of the measurements and remove all of the positive durations. I do this because you will always need the previous reflectivity measurement. Then i find the minimum of the absolute value of the duration and save the index in a new array.

x = refTT.('Time'); % this is unnecessary but I initialize arrays with the datetimes
y = [rawDataTT.('Var1')];
for n = 1:height(refTT) % take the time diff for each rawDataTT row
    time_diff(n,:) = x(n,1)-y(:,1);
end
time_diff(time_diff > 0) = NaN; %  remove positive durations
[~,I] = min(abs(time_diff(:,:)),[],'omitnan'); % find the minimum backwards duration
for k = 1:height(rawDataTT) % do the calculation with the index in I
    extinction(k,:) = refTT.('Reflectivity')(I(k),:) + ext_bath .*...
        (rawDataTT.('Spectra')(k,:);     
end