How to convert decimal time to HH:MM:SS

I have a dataset and the dates are being read by matlab in decimal time. I want it instead in 24 hour time as in the 'HH:MM:SS' format. If anyone knows a way to do it, please let me know. I've attached the dataset to this question

Thanks.

Answer 1

[Star Strider]

Try this (assuming that the decimal times are fractions of a day) —

T1 = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/1069395/General_Prompt_2.xlsx')

T1 = 73×6 table
           MetricWireID                  SurveyName           Prompt_SurveyStartedDate    Prompt_SurveyStartedTime    Prompt_SurveySubmittedDate    Prompt_SurveySubmittedTime
    __________________________    ________________________    ________________________    ________________________    __________________________    __________________________

    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          09-Mar-2022                   0.57934                    09-Mar-2022                     0.58215          
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          09-Mar-2022                   0.65731                    09-Mar-2022                     0.65907          
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          09-Mar-2022                   0.74525                    09-Mar-2022                     0.74794          
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          10-Mar-2022                   0.60737                    10-Mar-2022                     0.60931          
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          10-Mar-2022                   0.64112                    10-Mar-2022                     0.64244          
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          10-Mar-2022                   0.66376                    10-Mar-2022                     0.66542          
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          11-Mar-2022                   0.60443                    11-Mar-2022                     0.61084          
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          11-Mar-2022                   0.67159                    11-Mar-2022                     0.67269          
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          11-Mar-2022                   0.67733                    11-Mar-2022                     0.67868          
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          12-Mar-2022                   0.52457                    12-Mar-2022                     0.52628          
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          12-Mar-2022                   0.64763                    12-Mar-2022                     0.64926          
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          12-Mar-2022                   0.69402                    12-Mar-2022                     0.69516          
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          13-Mar-2022                   0.48693                    13-Mar-2022                     0.48904          
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          13-Mar-2022                   0.81632                    13-Mar-2022                     0.81744          
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          14-Mar-2022                   0.79081                    14-Mar-2022                     0.79255          
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          15-Mar-2022                   0.49403                    15-Mar-2022                     0.49538          

T1.Prompt_SurveySubmittedTime = datetime(T1.Prompt_SurveySubmittedTime, 'ConvertFrom','datenum', 'Format','HH:mm:ss');
T1.Prompt_SurveyStartedTime = datetime(T1.Prompt_SurveyStartedTime, 'ConvertFrom','datenum', 'Format','HH:mm:ss')

T1 = 73×6 table
           MetricWireID                  SurveyName           Prompt_SurveyStartedDate    Prompt_SurveyStartedTime    Prompt_SurveySubmittedDate    Prompt_SurveySubmittedTime
    __________________________    ________________________    ________________________    ________________________    __________________________    __________________________

    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          09-Mar-2022                   13:54:15                   09-Mar-2022                     13:58:18         
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          09-Mar-2022                   15:46:32                   09-Mar-2022                     15:49:04         
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          09-Mar-2022                   17:53:10                   09-Mar-2022                     17:57:02         
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          10-Mar-2022                   14:34:37                   10-Mar-2022                     14:37:24         
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          10-Mar-2022                   15:23:13                   10-Mar-2022                     15:25:07         
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          10-Mar-2022                   15:55:49                   10-Mar-2022                     15:58:12         
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          11-Mar-2022                   14:30:23                   11-Mar-2022                     14:39:37         
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          11-Mar-2022                   16:07:05                   11-Mar-2022                     16:08:40         
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          11-Mar-2022                   16:15:21                   11-Mar-2022                     16:17:18         
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          12-Mar-2022                   12:35:23                   12-Mar-2022                     12:37:51         
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          12-Mar-2022                   15:32:35                   12-Mar-2022                     15:34:56         
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          12-Mar-2022                   16:39:23                   12-Mar-2022                     16:41:02         
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          13-Mar-2022                   11:41:11                   13-Mar-2022                     11:44:13         
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          13-Mar-2022                   19:35:30                   13-Mar-2022                     19:37:07         
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          14-Mar-2022                   18:58:45                   14-Mar-2022                     19:01:16         
    {'98asd7asd80a9sd8a9d8ad'}    {'Questionnaire_Prompt'}          15-Mar-2022                   11:51:24                   15-Mar-2022                     11:53:21         

.

[BA]

This works perfectly, thanks!

[Star Strider]

As always, my pleasure!

Answer 2

[John D'Errico]

format long g
T = now % so the current time in a decimal format

T = 
          738720.618467535

The integer part of that time represents days, and above. The fractional part represents the fractions of a day. So a fractinoal part that is at least 0.5 is a time at least noon.

datestr(T,'hh:mm:ss')

ans = '14:07:35'

As you can see, the current time on the server is 2 PM, but the time shown shows a in 24 hour time format by default. So I'm not sure why you are asking. If you want it to show AM/PM, thus a 12 hour clock time, then you would do this:

datestr(T,'hh:mm:ss PM')

ans = ' 2:07:35 PM'