char to num (of datetime)

i'd like to change char to a numeric value so i can add it to my matrix.

my code:

t = datetime('now','Format','ydMHHmm');

x_num = str2double(t);

result:

x_num = NaN

i'd appretiate the help

[Davide Masiello]

Have you consider storing the values in a table instead? (That way, different column can be of different classes).

Answer 1

[Dyuman Joshi]

datetime() does not output string, it itself is an independent data type.

t = datetime('now','Format','y/d/M HH:mm')

t = datetime
   2022/11/10 08:39

If you want to convert it into a numerical value, you can use datenum (though it is not recommended as per the function documentation home page)

format long
datenum(t)

ans = 
     7.388053610059826e+05

[Steven Lord]

Alternately, you could define how long "1" is in terms of dates and times and use datetime and duration arithmetic. For example if you want a change of 1 in the double values to which the dates and times are mapped to represent 1 day of difference in the dates and times:

t = datetime('now','Format','y/d/M HH:mm')

t = datetime
   2022/11/10 13:21

c = datetime('December 25, 2022','Format','y/d/M HH:mm')

c = datetime
   2022/25/12 00:00

delta = days(c-t);
fprintf("It is %f days until Christmas!\n", delta)

It is 74.443398 days until Christmas!

If you're counting by minutes:

delta2 = minutes(c-t);
fprintf("It is %f minutes until Christmas!\n", delta2)

It is 107198.493499 minutes until Christmas!

Let's double check. There are this many minutes in a day:

mpd = delta2/delta

mpd = 1440

which we can check:

minutesPerDay = minutes(days(1))

minutesPerDay = 1440

I second the suggestion of @Davide Masiello to store your data in a table, though if you have time-based data a timetable array may be a better fit.