How to round datetime array to nearest minute?

Sounds like quite a easy question but i've spent a lot of time and cant find the answer. Basically I have a datetime array, i want to reduce the precision to minute so that second and beyond(millisecond etc.) are all changed to zero. is there any fast way to do so? Many Thanks

Answer 1

[Steven Lord]

You can use the dateshift function to do this. If you always want the result to be no later than the input, use 'start' on its own.

% Create some sample data
sampleData = datetime('now')

% Modify the display format of the sample data to show fractional seconds
sampleData.Format = 'dd-MMM-uuuu HH:mm:ss.SSS'

% Shift it to the start of the minute, throwing away seconds and fractional seconds
startOfMinute = dateshift(sampleData, 'start', 'minute')

If you want the result to be rounded to the start of the nearest minute, which could be later than the input datetime, use 'start' with 'nearest'.

% Create a sample datetime in the second half of the minute and set its format
sampleData = datetime(2017, 9, 14, 09, 52, 47.234, 'Format', ...
                      'dd-MMM-uuuu HH:mm:ss.SSS')

% Rounding should give 9:53 on September 14, 2017 since
% that's closer to sampleData than 9:52 on September 14, 2017
result = dateshift(sampleData, 'start', 'minute', 'nearest')

Answer 2

[Ziye]

Ok I just happen to find a solution by create a new datetime array using year month day hour minute second(0) of the original datetime array. but any other answers are welcomded

[Peter Perkins]

See Steve's suggestion below, i.e. dateshift.