Splitting date in a table into different columns

Hi all,

I'm using the 2019b version of Matlab and I'm currently handling a large dataset in a .csv format, which looks like this:

Date              Latitude            Longitude           Period
01/01/1980        23.9                57.3                2.32
01/01/1980        23.9                57.4                2.37
01/01/1980        24                  57.3                2.54
01/01/1980        24                  57.4                2.77
01/02/1980        23.9                57.3                2.18
01/02/1980        23.9                57.4                2.45
01/02/1980        24                  57.3                2.98
01/02/1980        24                  57.4                2.66

I've loaded it using readtable, which works just fine:

T=readtable(MyFile);
date=T(:,1);

I need to split the date into separate columns containing the day, month and year respectively, as later I'm planning to do group averaging of the data (i.e. calculate mean values of Period for different months, years and locations). I've tried:

a=datetime(date,'InputFormat','dd/MM/yyyy');

but I get the error message:

Error using datetime (line 659)
Input data must be a numeric array, a string array, a cell array containing character vectors, or a char matrix.

I'm not sure how to resolve it. Any help on this matter would be much appreciated!

Maja

[Stephen23]

You used the wrong kind of brackets. Instead of parentheses (which returns a table):

date=T(:,1);

you need to use curly braces (which returns whatever data type that column has):

date=T{:,1};

For more info: https://www.mathworks.com/help/matlab/matlab_prog/access-data-in-a-table.html

Answer 1

[Ameer Hamza]

You can use retime(): https://www.mathworks.com/help/matlab/ref/timetable.retime.html. No need to split the datetime column.

If you still want to seperate the column then use following methods

day(): https://www.mathworks.com/help/matlab/ref/datetime.day.html

month(): https://www.mathworks.com/help/matlab/ref/datetime.month.html

year(): https://www.mathworks.com/help/matlab/ref/datetime.year.html

[Maja Zdulska]

Thank you very much!