missing data, time series
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Johannes Deelstra
on 3 May 2019
Commented: Johannes Deelstra
on 15 May 2019
I am recording groundwater level at hourly intervalls using a data logger. I have data from 31 May 2017 09:00 hrs until 3 May 2019 03:00 hrs.
I noticed there are missing data as the total number of records should be 16843.
I generate a timeseries bb=[a1:ap:ae]; covering the indicated period where a1=datenum(2017,5,31,9,0,0), ap=datenum(0,0,0,1,0,0) and ae=datenum(2019,5,3,3,0,0) which gives the length of the time series being 16843
I read the logger data from excel into matlab with date in first column aa(:,1) while the second column (aa(:,2) contains the recorded logger data. I convert the Excel data to matlab data.
How can I now merge the data from aa with the dates in bb so that a second column (bb(:,2) has the reccorded logger data merged/combined with the correct date.
thanks before hand
Johannes
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Accepted Answer
Peter Perkins
on 14 May 2019
All you need to do is call retime and tell it what you want the new time v ecgtor to be. Sometimes it's as simple as 'hourly', other times you'll need to create a time vector yourself. It sounds like you want every hour represented. 'hourly' does that.
More Answers (2)
Peter Perkins
on 3 May 2019
Johannes, If I understand your question corre3ctly, you may want to consider using datetimes and a timetable. Not sure what form your data are in, but given a vector of values and a vector of timetstamps, both with a hole in them, this fills in the hole, in two different ways:
>> tt = timetable([1;2;4;5],'RowTimes',datetime(2019,5,3,[15 16 18 19],0,0))
tt =
4×1 timetable
Time Var1
____________________ ____
03-May-2019 15:00:00 1
03-May-2019 16:00:00 2
03-May-2019 18:00:00 4
03-May-2019 19:00:00 5
>> retime(tt,'hourly')
ans =
5×1 timetable
Time Var1
____________________ ____
03-May-2019 15:00:00 1
03-May-2019 16:00:00 2
03-May-2019 17:00:00 NaN
03-May-2019 18:00:00 4
03-May-2019 19:00:00 5
>> retime(tt,'hourly','spline')
ans =
5×1 timetable
Time Var1
____________________ ____
03-May-2019 15:00:00 1
03-May-2019 16:00:00 2
03-May-2019 17:00:00 3
03-May-2019 18:00:00 4
03-May-2019 19:00:00 5
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