Convert Julian Date to Calendar Days.

I'm trying to Convert the Julian-Time header to include the Year header and output the format mm/dd/yyyy. i.e. 12/31/2022 & 01/01/2023.

The complete data for Book1.xlsx contains multiple years.

Thank you!

Answer 1

[Cris LaPierre]

Perhaps a bit convoluted, but this appears to work. I haven't compared it extensively to the orginal data. Note that the display format only modifies how the data appears. The time is still there.

data = readtable('Book1.xlsx',"TextType","string");

Warning: Column headers from the file were modified to make them valid MATLAB identifiers before creating variable names for the table. The original column headers are saved in the VariableDescriptions property.
Set 'VariableNamingRule' to 'preserve' to use the original column headers as table variable names.

% your Julian_dates are surrounded by quotes. Remove them
data.Julian_Time = erase(data.Julian_Time,"'");
% use datetime to convert the combined date string to a datetime.
% DDD indicates day-of-year
data.Julian_Time = datetime(data.Year+"-"+data.Julian_Time,'InputFormat','uuuu-DDD-HH:mm:ss.SSS');
data.Julian_Time.Format = 'MM/dd/yyyy'

data = 185×4 table
    Year    Julian_Time    Data1     Data2 
    ____    ___________    ______    ______

    2022    12/31/2022     36.425    21.998
    2022    12/31/2022     36.725    21.998
    2022    12/31/2022     36.425    21.998
    2022    12/31/2022     36.425    21.998
    2022    12/31/2022     36.725    21.998
    2022    12/31/2022     36.725    21.998
    2022    12/31/2022     36.425    21.998
    2022    12/31/2022     36.425    21.998
    2022    12/31/2022     36.425    21.998
    2022    12/31/2022     36.725    21.998
    2022    12/31/2022     36.725    21.998
    2022    12/31/2022     36.425    21.998
    2022    12/31/2022     36.425    21.998
    2022    12/31/2022     36.725    21.998
    2022    12/31/2022     36.425    21.998
    2022    12/31/2022     36.425    21.998