Divide table in days and then in hours.

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Erica Corradi
Erica Corradi on 16 Jun 2018
Commented: Stephan on 26 Jun 2018
Hello everyone! I'm not very practical with matlab, so I hope that someone can help me. I have a big table [351496 x 5] that it contains 6 months of monitoring. Below the first five rows of my table.
The first column is the categorical variable (they are the name of my PIR sensors) the last column (ColumnDateTime) is the date time array. I want to divide my table for days, so as to create daily subtables. then, every daily subtable I would divide it by hours, creating 4 additional tables (which correspond to the times of the day: morning, afternoon, evening, night). Then I would like to analyze if there are 2 PIR sensors that detect movements in two different rooms (the different rooms are recognized in the first column, through the names of the sensors) in a time <= to 2 seconds. Thanks in advance.

Accepted Answer

Stephan on 22 Jun 2018
if you use a timetable for storing your data the function that might help you is
With this function you can aggregate your data among other things. There are also examples given on the retime documentation site.
Best regards
Stephan on 26 Jun 2018
Nice to hear... have fun

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More Answers (1)

Razvan Carbunescu
Razvan Carbunescu on 26 Jun 2018
Depending on the final goal here could use some of the functionality within groupsummary (If using R2018a) and findgroups / splitapply models to help achieve some of the final modeling.
>> groupsummary(tab,'t',hours(6),'mean','values')
ans =
12×3 table
disc_t GroupCount mean_values
____________________________________________ __________ ___________
[01-Jun-2018 00:00:00, 01-Jun-2018 06:00:00) 6 58.833
[01-Jun-2018 06:00:00, 01-Jun-2018 12:00:00) 6 61.167
[01-Jun-2018 12:00:00, 01-Jun-2018 18:00:00) 6 41.167
[01-Jun-2018 18:00:00, 02-Jun-2018 00:00:00) 6 56.5
[02-Jun-2018 00:00:00, 02-Jun-2018 06:00:00) 6 59.667
[02-Jun-2018 06:00:00, 02-Jun-2018 12:00:00) 6 42.167
[02-Jun-2018 12:00:00, 02-Jun-2018 18:00:00) 6 50.333
[02-Jun-2018 18:00:00, 03-Jun-2018 00:00:00) 6 30.667
[03-Jun-2018 00:00:00, 03-Jun-2018 06:00:00) 6 40
[03-Jun-2018 06:00:00, 03-Jun-2018 12:00:00) 6 43.833
[03-Jun-2018 12:00:00, 03-Jun-2018 18:00:00) 6 69.333
[03-Jun-2018 18:00:00, 04-Jun-2018 00:00:00] 6 62.167

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