Converting time data to plot

I imported an excel file (xlsread) and the time data turned into decimal form. I wrote the following code get a what I think is called a character array of just times.

um_time = num(:,1);
theDate = char(datetime(num_time,'ConvertFrom','excel')); % or 'excel1904'
theTimes = theDate(:,end-7:end);

The output for theTimes variable looks like this

val =

19:17:10
19:17:10
19:17:10
19:17:10
....

The problem that I have is that I can't use the variable theTimes in a plot function.

How can I turn theTimes values into a column vector of values that I can use to plot?

Answer 1

[Adam Danz]

After you convert to datetime, keep it in datetime format. There's no need to convert it to char.

From r2016b onward, you can use datetime objects in plot().

datetime(num_time,'ConvertFrom','excel')

Here's several of examples

https://www.mathworks.com/help/matlab/matlab_prog/plot-dates-and-durations.html

[addendum]

If you're reading the dates in from excel you can read them in as datetime.

m = readmatrix('Dates.xlsx','OutputType','datetime'); 

[Ryan McBurney]

I figured out a different approach.

I used readtable() instead of xlsread. I used this code as well:

data = readtable(filename,'Range','A22:Y432');
data.Time = datetime(datevec(data.Time),'Format','HH:mm:ss.SSS');

The second line in the code solved my problem.

Thanks for the nudge in the right direction.

[Adam Danz]

I just updated my answer to add another approach similar to yours.

If you're going to use readtable(), you could use the DateTimeType name-value input instead of doing the conversion in your comment above.