MATLAB: Filling gaps in time series with Nan

dataseriesnan

Hi there!
I^m currently working with several series of data from different sensor.Each sensor is measuring different quantities, and, theoretically, should provide a value each 30s, so that in 1 day I should have 2880 values for each sensor. I have a matrix for each sensor with 2 columns: timestamp and the corresponding measured data. The problem is that sometime some sensors just misses the measure (very randomly) and they do not record gaps as anything, they simply skip to the next measure, so the length of the matrixes is never 2880, but always shorter and different between the sensors. What i would like to do is to detect these gaps in the timestamp column and to insert Nan values in the corresponding data column. If anyone could offer any suggestions it would be very much appreciated!
PS: the timestamp column is already in Matlab time format: (2013-03-01=735294) (30s=-3.4722e-004)
Thanks!!!!

Best Answer

Sounds like a job for intersect():
%Generating random dataset:
numVals = 2000;
all_seconds = 0:30/86400:1;
all_seconds(end) = [];
all_seconds = all_seconds' + floor(now);
your_seconds = all_seconds(sort(randperm(numel(all_seconds),2000)));
your_data = [your_seconds rand(numVals,1)];
%Actually doing what you asked:
filled_data = [all_seconds NaN(numel(all_seconds),1)];
[bla ia ib] = intersect(filled_data(:,1),your_data(:,1));
filled_data(ia,2) = your_data(ib,2);
Please accept an answer if it helps you.
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