Datetime won't recognise some cells

I have a series of datetimes in the format 'HH:mm:ss.sss'. I am using the following code to convert from string into datetimes.

data.TimeofDay = datetime(data.TimeofDay,'Format','HH:mm:ss.sss')

Unable to resolve the name 'data.TimeofDay'.

In the attached .mat file, it contains the data file before and after the command above. For some reason, different values in the column are returned as NaT despite all rows seemingly being in the same format.

[the cyclist]

Relevant for both your code and some of the answers:

• 'Format' governs what the output looks like
• 'InputFormat' governs what the input looks like

In your case, I believe MATLAB would have correctly inferred your input format, if had you left it unspecified:

datetime(data.TimeofDay)

Answer 1

[Cris LaPierre]

For miliseconds, you want to use a capital 'S'.

load datetime-problem.mat

datetime(databackup.TimeofDay,'Format','HH:mm:ss.sss')

ans = 14×1 datetime array
   09:03:26.026
   NaT         
   NaT         
   NaT         
   NaT         
   09:10:47.047
   NaT         
   NaT         
   NaT         
   09:16:15.015
   NaT         
   NaT         
   NaT         
   NaT         

% corrected
datetime(databackup.TimeofDay,'Format','HH:mm:ss.SSS')

ans = 14×1 datetime array
   09:03:32.026
   09:05:04.939
   09:06:32.609
   09:07:58.886
   09:09:23.436
   09:10:48.047
   09:12:12.351
   09:13:42.538
   09:15:07.079
   09:16:41.015
   09:36:12.951
   09:37:52.603
   09:39:16.163
   09:40:41.993

Answer 2

[the cyclist]

Two minor but important changes to your syntax:

datetime(data.TimeofDay,'InputFormat','HH:mm:ss.SSS')

Note that I used

• 'InputFormat' instead of 'Format'
• .SSS instead of .sss

Answer 3

[Voss]

load datetime-problem.mat
databackup.TimeofDay

ans = 14×1 string array
    "09:03:32.026"
    "09:05:04.939"
    "09:06:32.609"
    "09:07:58.886"
    "09:09:23.436"
    "09:10:48.047"
    "09:12:12.351"
    "09:13:42.538"
    "09:15:07.079"
    "09:16:41.015"
    "09:36:12.951"
    "09:37:52.603"
    "09:39:16.163"
    "09:40:41.993"

% original Format specification:
datetime(databackup.TimeofDay,'Format','HH:mm:ss.sss')

ans = 14×1 datetime array
   09:03:26.026
   NaT         
   NaT         
   NaT         
   NaT         
   09:10:47.047
   NaT         
   NaT         
   NaT         
   09:16:15.015
   NaT         
   NaT         
   NaT         
   NaT         

% corrected Format specification:
datetime(databackup.TimeofDay,'Format','hh:mm:ss.SSS')

ans = 14×1 datetime array
   09:03:32.026
   09:05:04.939
   09:06:32.609
   09:07:58.886
   09:09:23.436
   09:10:48.047
   09:12:12.351
   09:13:42.538
   09:15:07.079
   09:16:41.015
   09:36:12.951
   09:37:52.603
   09:39:16.163
   09:40:41.993