MATLAB: How to change data from 10 minutes to hour

#convert #hour #minutes

I have data

x =

01/02/2015 02:20 4

02/02/2015 2:30 2

01/02/2015 02:50 0

01/02/2015 08:50 8

01/02/2015 03:00 7

01/02/2015 03:10 9

02/02/2015 3:30 4

02/02/2015 3:40 6

02/02/2015 03:50 8

…

the first step I want to normalize starts from the initial hour (2:00)

and generate data per 10 minutes with empty data filled with Nan

the second step I want to change it to average data per hour … so that i get hourly data on each date …

I have tried many times but this doesn't work ..

I thank all those who gave advice and were kind enough to help me.

Best Answer

In R2016b:

T = readtable('data.txt','ReadVariableNames',false,'Format','%q %q %f');
TT = sortrows(timetable(T.Var3,'RowTimes',...
    datetime(strcat(T.Var1,'_',T.Var2),'I','dd/MM/uuuu_HH:mm')));
dt = dateshift(TT.Time(1),'start','hour'):...
    minutes(10):dateshift(TT.Time(end),'end','hour');
TT1 = retime(TT,dt);% data per 10 minutes
TT2 = retime(TT,'hourly','mean');% average data per hour

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MATLAB: Timezone to UTC: How to add duration vector to datetime vector

Frank, what's up is Daylight Saving Time, which occurred on March 8th this year. I'm guessing you knew that, but got mixed up in the time arithmetic. Here's what's going on. You have this:

>> time = ['2015/03/08 00:00';'2015/03/08 01:00';'2015/03/08 03:00';'2015/03/08 04:00'];
>> Time = datenum(time,'yyyy/mm/dd HH:MM')
Time =
                    736031
          736031.041666667
                736031.125
          736031.166666667

datenums don't know anything about time zones or DST. Those times mean whatever you want them to mean. Since you then do this ...

>> date = datetime(Time,'ConvertFrom','datenum','Timezone','America/Montreal')
date = 
   08-Mar-2015 00:00:00
   08-Mar-2015 01:00:00
   08-Mar-2015 03:00:00
   08-Mar-2015 04:00:00

... I assume you mean that those datenums are to be interpreted as times in the America/Montreal time zone. But what you've left out is this:

>> date.Format = [date.Format ' z']
date = 
   08-Mar-2015 00:00:00 UTC-5
   08-Mar-2015 01:00:00 UTC-5
   08-Mar-2015 03:00:00 UTC-4
   08-Mar-2015 04:00:00 UTC-4

The second and third times are only an hour apart. Then this ...

>> [UTC_Offset,dst] = tzoffset(date);
>> Date = date - UTC_Offset
Date = 
   08-Mar-2015 06:00:00 UTC-4
   08-Mar-2015 07:00:00 UTC-4
   08-Mar-2015 07:00:00 UTC-4
   08-Mar-2015 08:00:00 UTC-4

... adds 5 hours to the first and second times, but adds only 4 hours to the third and fourth times. But you're doing the addition in the America/Montreal time zone. Adding 5 hours to the first two puts them after the DST shift @2am, which makes them look like you added 6 hours. In other words, your array is not UTC, it's shifted America/Montreal. The easiest thing to do to get UTC times is this:

>> date.TimeZone = 'UTC'
date = 
   08-Mar-2015 05:00:00 UTC
   08-Mar-2015 06:00:00 UTC
   08-Mar-2015 07:00:00 UTC
   08-Mar-2015 08:00:00 UTC

Hope this helps.

MATLAB: Creating date for data sorting in time series data

If you have R2016b or later, it might be easiest to create a timetable() and use retime()

Best Answer

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MATLAB: Timezone to UTC: How to add duration vector to datetime vector

MATLAB: Creating date for data sorting in time series data

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