Problems with datestr()

Hello everyone, I am currently trying to use datestr on datetimes

string_data = datestr(data_datetime);

however it returns an error as follows:

Subscript indices must either be real positive integers or logicals.

Error in formatdate (line 157)
            month = char(strrep(month(dtvector(:,2)), '.', '')); %remove period

Error in dateformverify (line 32)
S = char(formatdate([y,mo,d,h,minute,s],dateformstr,islocal));

Error in datestr (line 199)
S = dateformverify(dtnumber, dateformstr, islocal);

Error in datetime/datestr (line 768)
            s = datestr(datenum(this),varargin{:});

I don't undertand why it doesn't work :(

I've attached the .mat file along with this question.

Thanks in advance.

Arthur.

Answer 1

[Star Strider]

The problem is that 25 of ‘data_datetime’ is NaT (not a time, analogous to NaN, not a number). The datenum function cannot convert NaT to anything.

D = load('datetimes.mat');
dt = D.data_datetime;
natv = nnz(isnat(dt))

produces:

natv =
    25

One option is to simply interpolate the times:

dtfm = fillmissing(dt,'linear');
s = datestr(datenum(dtfm));

That runs without error.

See the documentation on fillmissing to explore other interpolation options.