`dateshift`

Moves datetime values to the start or end of a time unit.

Category: Language Fundamentals > Data Types

Syntax

t2 = dateshift(t, 'start', unit)

Start of the unit that contains each element.

t2 = dateshift(t, 'end', unit)

End of that unit.

Description

dateshift(t,'start','month') gives midnight on the first day of the month. The end of a unit is the last instant before the next one begins, which displays as the last date of the unit. A week starts on Sunday.

This is the standard way to group dates by month or year, for example before a groupsummary.

Input arguments

t: datetime array.
unit: 'year', 'month', 'week' or 'day'.

Output arguments

t2: datetime array with the size of t.

Example

Month and year boundaries

t = datetime(2020,5,17,13,30,0);
dateshift(t, 'start', 'month')
dateshift(t, 'end', 'month')
dateshift(t, 'start', 'year')

Output

ans = datetime
   01-May-2020
ans = datetime
   31-May-2020
ans = datetime
   01-Jan-2020

Notes

The 'dayofweek' form (moving to the next Monday, for example) may return the input date unchanged in MatLivre.

dateshift