datestr on UTC time '2016-12-1​9T08:00:00​.000Z' failing

Hi,

I am trying to convert ISO date and time string into cell array. My original data has a format of '2016-12-19T08:00:00.000Z'.

If I run the matlab code in the format below, it generates an error saying "Error using datestr (line 177) Cannot convert input into specified date character vector. DATENUM failed."

ds2 = datestr(out2{1,1}, 'yyyy-mm-ddTHH:MM:SSZ');

Can you find why is it generating an error? I think date formatting('yyyy-mm-ddTHH:MM:SSZ') is not correct.

Answer 1

[Walter Roberson]

Z is not one of the permitted letters for datestr. Although you can add characters like : or / to be matched literally, the literal matches are restricted to non-alphabetic characters.

If you have r2013b or later then datetime is recommended. Note the character codes are different with datetime to match international standards

[Joyce Shin]

I just tried removing Z from the format, however, it complains with an error:

Expression or statement is incomplete or incorrect.

If I replace datestr with datetime, it gives me the same error. BTW, I am using R2016b.

[Walter Roberson]

T is not in the letters permitted by datestr() either.

https://www.mathworks.com/help/matlab/ref/datetime.html#bundhic

S = '2016-12-19T08:00:00.000Z';
datetime(S, 'InputFormat', 'yyyy-MM-dd''T''hh:mm:ss.sssZ', 'TimeZone', 'UTC')

[Joyce Shin]

I tried this method and some of the gave me the correct output. However, some of the cells are filled with "NaT". 240/6720 is converted correctly. How should I fix the code?

[Walter Roberson]

Could you give an example of a string that is not converted, and the time that you expect it to be converted to?

[Peter Perkins]

As Walter says, it sounds like some (most?) of your strings are not in that format. If you have two formats, the solution is to do it in two steps, something like

d = datetime(s,'InputFormat',format1)
failed = isnat(d);
d(failed) = datetime(s(failed),'InputFormat',format2)

Answer 2

[Jan]

Try FEX: DateStr2Num:

DateStr2Num('2016-12-19T08:00:00.000Z', 31)

This uses the 'yyyy-mm-dd HH:MM:SS' format ignoring the 'T', the 'Z' and the fractional seconds.