For tabularTextDatastore, how do I specify a column as a datetime or duration

I have many csv files of time history data. If I create a tabularTextDatastore:

ttds = tabularTextDatastore("C:/myfiles");
myttds = ttds.preview

I get:

myttds = 8x414 table

Time TimeOfDay WT1DCBusVoltage1 WT10ACCurrentAPhase

__________ ______________ _________________ ___________________

63.9609375 59117.1640625 0.155702099204063 1.50458014011383

63.9921875 59117.203125 0.204921007156372 1.51381540298462

64.0234375 59117.234375 0.193629086017609 1.50028717517853

64.0546875 59117.26171875 0.137909501791 1.49814927577972

64.0859375 59117.29296875 0.137250736355782 1.50692522525787

64.1171875 59117.32421875 0.16432049870491 1.51645302772522

64.1484375 59117.35546875 0.159727975726128 1.50788652896881

64.1796875 59117.38671875 0.159778669476509 1.51117658615112

(the rest of the columns are omitted)

but I want it to be a timetable datastore, so I tried:

ttds = tabularTextDatastore(fs,"RowTimes",'Time');

and get error:

The row times variable 'Time' must be of type datetime or duration

How do I specify that "Time" is a duration of seconds? I tried to convert the format using:

istime = cellfun(@(x)isequal(x,"Time"),ttds.SelectedVariableNames);
ttds.SelectedFormats(istime) = {'%{ss.SSSSSSSSSS}T'};
myttds = ttds.preview

but still get an error:

"ss.SSSSSSSSSS" is not a valid duration format.

Answer 1

[Gayatri Rathod]

Hi Matthew,

To specify a column as a datetime or duration in a tabularTextDatastore, you need to first convert the column to the appropriate data type before creating the datastore.

Below are the steps to convert the "Time" column to a duration of seconds:

 % Load the data into a table
 mytable = readtable("C:/myfiles/mydata.csv"); 
 
 % Convert the "Time" column to a duration of seconds
 mytable.Time = seconds(mytable.Time);
 
 % Create a timetable from the table
 mytimetable = table2timetable(mytable, 'RowTimes', 'Time');
 
 % Save the timetable as a MAT file 
 save("mytimetable.mat", "mytimetable"); 
 
 % Load the timetable from the MAT file 
 mytimetable = load("mytimetable.mat", "mytimetable").mytimetable; 
 
 % Create a tabularTextDatastore from the timetable
 ttds = tabularTextDatastore("mytimetable.mat", "ReadFcn", @load, "SelectedVariableNames", {'Time', 'WT1DCBusVoltage1', 'WT10ACCurrentAPhase'}); 

This will create a tabularTextDatastore that only includes the "Time", "WT1DCBusVoltage1", and "WT10ACCurrentAPhase" columns.

You can read more about the tabularTextDatastore, seconds and table2timetable functions from the following documentations:    tabulartextdatastore Function, seconds Function, table2timetable Function.

Hope it helps!

Regards,

Gayatri Rathod