how to shift datetime to account for daylight savings time

The source data I am using expresses times in Coordinated Universal Time (UTC). I need to derive a MATLAB datetime array shifted correctly for daylight savings time throughout the year. It seems to me this ought to be straightforward, but I am finding this datetime business quite confusing. I simply want to shift times by one hour to account for DST. I am in the New York time zone.

If I put a datetime array into isdst, it does not return the correct answers (I get all logical zeros).

Thanks

Answer 1

[Star Strider]

If you’ve not already explored it, the TimeZone property may be helpful.

Also see Specify Time Zones since it appears that ‘A different time zone offset is displayed depending on whether the datetime occurs during daylight saving time.’ according to the documentation.

[Kevin Johnson]

r=size(retrieved_data.results,1);
dt=NaT(r,1);
dt.TimeZone='America/New_York';
for g=1:r
    utc=retrieved_data.results{g}.t*0.001; 
    dt(g)=datetime(utc,'ConvertFrom','posixtime','TimeZone','America/New_York');
end 

[Kevin Johnson]

This works, thanks.

[Star Strider]

As always, my pleasure!

[Peter Perkins]

Kevin, it looks like your retrieved_data.results is a cell array scalar structs containing POSIX times in their t field, in ms since 1970? Maybe? If round-off issues are a concern, you might consider using 'epochtime' and 'TicksPerSecond' instead of 'posixtime'.

In any case, if your code works for you, that's great. but there ought to be a way to vectorize this calculation down to something without loops, like maybe

results = [results{:}];
utc = [results.t];
dt = datetime(utc,'ConvertFrom','posixtime','TimeZone','America/New_York');

[Kevin Johnson]

Those are interesting ideas. I'll give them a try. Thanks!

Kevin