Rounding UTC times down help

Hi, I'm trying to round times down to 10 mins at intervals 5, 15, 25, 35, 45, 55 mins. The format i'm using is yyyy-mm-dd hh:mm:ss in a table.

I have tried:

data_lables.UTC = datetime(data_lables.UTC);
vec = datevec(data_lables.UTC);
v5  = vec(:,5)+vec(:,6)/60;
vec(:,5) = round(v5/10)*10;
vec(:,6) = 0;
data_lables.UTC = datetime( vec );

but this rounds to 00, 10, 20 ,30 ,40 ect.

[dpb]

Use retime with desired duration vector...

[Alistair Walker]

Thank you, though i'm not sure how that would look in my case..

[dpb]

>> minutes(5:10:100)
ans = 
  1×10 duration array
    5 min   15 min   25 min   35 min   45 min   55 min   65 min   75 min   85 min   95 min
>> 

[Alistair Walker]

though when I do this I get the error

(>> TT2 = retime(data_lables.UTC,'regular','linear','TimeStep',dt) Undefined function 'retime' for input arguments of type 'datetime'.)

the code im using is :

data_lables.UTC = datetime(data_lables.UTC);
t1=data_lables.UTC(1:1) %start time 12-Nov-2019 16:26:35
t2=data_lables.UTC(length(data_lables.UTC))%end time 22-Nov-2019 08:05:44
t11=datevec(datenum(t1));
t22=datevec(datenum(t2));
duration= etime(t22,t11)%time_interval_in_seconds
duration_min=duration/60
dt = minutes(5:10:duration_min);
TT2 = retime(data_lables.UTC,'regular','linear','TimeStep',dt)

[dpb]

The input to use retime has to be a timetable, true...

Alternatives would be far easier to try to write if saw what the data are and knew what you're trying to do with other data -- interpolate, bin, or just reset the time vector. If it's just the latter and they're even, roughly, then just writing the desired timestamp might be the simplest.

Answer 1

[Cris LaPierre]

I'm not aware of a built-in way to do this. I'd try something like this

data_lables.UTC = datetime(data_lables.UTC);

% get date components
v = datevec(data_lables.UTC)

% Round minutes to previous 5 minute increments
v(:,5) = floor(v(:,5)/5)*5;
% Set seconds to zero
v(:,6)= 0;

% Update table varible
data_lables.UTC = datetime(v);

While it doesn't work for rounding to 5 minute increments, you might look into the dateshift function.

[Alistair Walker]

Thank you to you both for your help! this code worked!

[Peter Perkins]

Best to try to avoid mixing datetime with the older date/time functions (though in this case Chris's suggestion is fine). Use the datetime's properties:

min = data_lables.UTC.Minute;
data_lables.UTC.Minute = floor(min/5)*5;
data_lables.UTC.Second = 0;

As dpb says, if your times are the row times of a timetable, retime has you covered.