MATLAB Answers

sorting table according to date/time

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Ben Keshet
Ben Keshet on 28 Oct 2020
Answered: Steven Lord on 28 Oct 2020
I have a table with a TimeStamp column with the format '6/29/2020 12:39:32.910 AM'. I want to sort the table in acesending order but by default Matlab treats the column as a string. I have tried using datetime to define the column as dat format:
>> t=datetime(T1T2.TimeStamp,'InputFormat', 'MM/DD/yyyy HH:mm:ss.sss')
which failed, probably becasue I am not defining the AM/PM symbols.
What is the best/easiest way to sort this table according to the date value?
Many thanks,

Accepted Answer

Star Strider
Star Strider on 28 Oct 2020
There are problems with the 'InputFormat' format string.
Try this:
t=datetime(T1T2.TimeStamp,'InputFormat', 'MM/dd/yyyy hh:mm:ss.SSS a')
t =
29-Jun-2020 00:39:32
Note that the hours need to be ‘hh’ not ‘HH’ for AM/PM times, the days are ‘dd’ not ‘DD’, and the ‘a’ denotes that the format is in AM/PM. (I created a temporary variable to replace the table reference to test this and make certain that it works.)

More Answers (2)

KSSV on 28 Oct 2020
Convert the dates you have into class of datetime using the function datetime and then you can use sort function. Read about datetime.

Steven Lord
Steven Lord on 28 Oct 2020
which failed, probably becasue I am not defining the AM/PM symbols.
According to the table in the description of the Format property of datetime objects include the character a in the Format and/or InputFormat values to handle AM/PM. I had to make three additional changes to your InputFormat, each prompted by a warning and/or error message.
Using HH for hours in 24-hour clock notation is incompatible with also specifying the day period (AM/PM) so I changed it to hh (hour, 12-hour clock notation.)
Using MM (month) and DD (day of year) are incompatible, so I changed DD to dd (day of month).
Lower-case ss is for seconds, upper-case S are for the digits of fractional seconds.
s = '6/29/2020 12:39:32.910 AM'
t=datetime(s,'InputFormat', 'MM/dd/yyyy hh:mm:ss.SSS a')


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