How do I truncate a table based on a data window I'd like to use?

Hello,

I have a table with a DateTime group in the first column. It runs from midnight to midnight on a certain day. I would like to truncate the hours to between 8:00 AM and 3:00 PM, and discard all other data in the table. Is there a way to do this, or do I have to translate the date-time to something different to perform this operation? Thank you.

Answer 1

[Voss]

% I construct a table similar to yours:
TimeReceived = datetime(2023,6,26,0,0,(0:60*60*24-1).',2.6,'Format','dd-MMM-yyyy HH:mm:ss.SSSSSSSSS');
N = numel(TimeReceived);
TimeSent = 1.6878e18*ones(N,1);
RecordType = 160*ones(N,1);
T = table(TimeReceived,TimeSent,RecordType)

T = 86400×3 table
             TimeReceived              TimeSent     RecordType
    ______________________________    __________    __________

    26-Jun-2023 00:00:00.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:01.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:02.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:03.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:04.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:05.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:06.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:07.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:08.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:09.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:10.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:11.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:12.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:13.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:14.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:15.002600000    1.6878e+18       160    

% keep only rows of T where TimeReceived is between 8 AM and 3 PM inclusive
tod = timeofday(T.TimeReceived);
idx = tod >= hours(8) & tod <= hours(15);
T = T(idx,:)

T = 25200×3 table
             TimeReceived              TimeSent     RecordType
    ______________________________    __________    __________

    26-Jun-2023 08:00:00.002600000    1.6878e+18       160    
    26-Jun-2023 08:00:01.002600000    1.6878e+18       160    
    26-Jun-2023 08:00:02.002600000    1.6878e+18       160    
    26-Jun-2023 08:00:03.002600000    1.6878e+18       160    
    26-Jun-2023 08:00:04.002600000    1.6878e+18       160    
    26-Jun-2023 08:00:05.002600000    1.6878e+18       160    
    26-Jun-2023 08:00:06.002600000    1.6878e+18       160    
    26-Jun-2023 08:00:07.002600000    1.6878e+18       160    
    26-Jun-2023 08:00:08.002600000    1.6878e+18       160    
    26-Jun-2023 08:00:09.002600000    1.6878e+18       160    
    26-Jun-2023 08:00:10.002600000    1.6878e+18       160    
    26-Jun-2023 08:00:11.002600000    1.6878e+18       160    
    26-Jun-2023 08:00:12.002600000    1.6878e+18       160    
    26-Jun-2023 08:00:13.002600000    1.6878e+18       160    
    26-Jun-2023 08:00:14.002600000    1.6878e+18       160    
    26-Jun-2023 08:00:15.002600000    1.6878e+18       160    

[Timothy]

Thanks!

[Voss]

You're welcome!

Answer 2

[Seth Furman]

Alternatively you can use timerange.

TimeReceived = datetime(2023,6,26,0,0,(0:60*60*24-1).',2.6,'Format','dd-MMM-yyyy HH:mm:ss.SSSSSSSSS');
N = numel(TimeReceived);
TimeSent = 1.6878e18*ones(N,1);
RecordType = 160*ones(N,1);
tt = timetable(TimeReceived,TimeSent,RecordType)

tt = 86400×2 timetable
             TimeReceived              TimeSent     RecordType
    ______________________________    __________    __________

    26-Jun-2023 00:00:00.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:01.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:02.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:03.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:04.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:05.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:06.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:07.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:08.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:09.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:10.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:11.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:12.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:13.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:14.002600000    1.6878e+18       160    
    26-Jun-2023 00:00:15.002600000    1.6878e+18       160    

tr = timerange(datetime(2023,6,26,8,0,0),datetime(2023,6,26,15,0,0),"closed");
tt = tt(tr,:);
head(tt)

             TimeReceived              TimeSent     RecordType
    ______________________________    __________    __________

    26-Jun-2023 08:00:00.002600000    1.6878e+18       160    
    26-Jun-2023 08:00:01.002600000    1.6878e+18       160    
    26-Jun-2023 08:00:02.002600000    1.6878e+18       160    
    26-Jun-2023 08:00:03.002600000    1.6878e+18       160    
    26-Jun-2023 08:00:04.002600000    1.6878e+18       160    
    26-Jun-2023 08:00:05.002600000    1.6878e+18       160    
    26-Jun-2023 08:00:06.002600000    1.6878e+18       160    
    26-Jun-2023 08:00:07.002600000    1.6878e+18       160    

tail(tt)

             TimeReceived              TimeSent     RecordType
    ______________________________    __________    __________

    26-Jun-2023 14:59:52.002600000    1.6878e+18       160    
    26-Jun-2023 14:59:53.002600000    1.6878e+18       160    
    26-Jun-2023 14:59:54.002600000    1.6878e+18       160    
    26-Jun-2023 14:59:55.002600000    1.6878e+18       160    
    26-Jun-2023 14:59:56.002600000    1.6878e+18       160    
    26-Jun-2023 14:59:57.002600000    1.6878e+18       160    
    26-Jun-2023 14:59:58.002600000    1.6878e+18       160    
    26-Jun-2023 14:59:59.002600000    1.6878e+18       160