Compare Dates and Times Using Relational Operators

Relational operators compare arrays quantitatively, using operators such as "less than," "greater than," and "equal to." The result of a relational comparison is a logical array indicating the locations where the relation is true.

The datetime and duration data types represent dates and times quantitatively. To compare such arrays, you can use the same relational operators that you use to compare numeric arrays. However, the comparisons have meanings that are slightly different, depending on the data type.

Relational Operator	Meaning When Comparing datetime Values	Meaning When Comparing duration Values
<	Before	A shorter length of time than
<=	Either before or at the same date and time as	Either a shorter length of time than or the same length of time as
>	After	A longer length of time than
>=	Either after or at the same date and time as	Either a longer length of time than or the same length of time as
==	At the same date and time as	The same length of time as
~=	Not at the same date and time as	Not the same length of time as

Note: The calendarDuration data type does not support comparisons using relational operators. Calendar years, quarters, months, weeks, and days do not necessarily represent fixed lengths of time, thanks to leap years, months of different lengths, daylight saving time, and leap seconds.

Compare Dates and Times

You can compare two datetime arrays to each other, and you can compare two duration arrays to each other. The arrays must have compatible sizes because relational operators perform elementwise comparisons. In the simplest cases, the two arrays have the same size or one is a scalar. In more complex cases, MATLAB® implicitly expands arrays with compatible sizes to be the same size during the comparison. For more information, see Compatible Array Sizes for Basic Operations.

Also, you can compare datetime and duration arrays to:

• Text. When you compare text to a datetime or duration array, MATLAB implicitly converts the text to the datetime or duration value that it represents.

• Numbers. When you compare a number to a duration array, MATLAB implicitly converts that number to a duration value that is the equivalent number of days.

You cannot compare a datetime array and a duration array. However, you can compare components of datetime arrays to numbers or to duration arrays.

Compare datetime Arrays

Create a datetime array. To convert text representing a date and time, use the datetime function.

D1 = datetime("2022-06-05 11:37:05")

D1 = datetime
   05-Jun-2022 11:37:05

You can also convert numbers to datetime arrays. The input numeric arrays represent datetime components—years, months, days, hours, minutes, and seconds.

D2 = datetime(2022,2:4:10,15,12,0,0)

D2 = 1x3 datetime
   15-Feb-2022 12:00:00   15-Jun-2022 12:00:00   15-Oct-2022 12:00:00

Compare the two datetime arrays. The result shows which elements of D2 occur after D1.

TF = D1 < D2

TF = 1x3 logical array

   0   1   1

To create a new datetime array containing only the matching elements, index into D2 using TF.

afterD1 = D2(TF)

afterD1 = 1x2 datetime
   15-Jun-2022 12:00:00   15-Oct-2022 12:00:00

Text and datetime Arrays

If you have text that represents dates and times, and it is formatted in a way that the datetime function recognizes, then you can compare the text to a datetime array. The comparison implicitly converts the text.

For example, compare a string that represents June 1, 2022 to D2. The first element of D2 occurs before June 1. (If you specify a date only, then the time is set to midnight.)

TF = D2 >= "2022-06-01"

TF = 1x3 logical array

   0   1   1

afterJune1 = D2(TF)

afterJune1 = 1x2 datetime
   15-Jun-2022 12:00:00   15-Oct-2022 12:00:00

Components of datetime Arrays

The datetime data type provides access to the components of datetime values. Access components by using the year, quarter, month, day, hour, minute, and second functions. You can compare components to numbers or duration values because these functions return numbers.

For example, display the datetime array D2. Then display its month component.

D2

D2 = 1x3 datetime
   15-Feb-2022 12:00:00   15-Jun-2022 12:00:00   15-Oct-2022 12:00:00

M = month(D2)

M = 1×3

     2     6    10

To find the elements of D2 that occur before the month of June, compare D2 to the numeric value corresponding to June. Then index into D2.

TF = month(D2) < 6

TF = 1x3 logical array

   1   0   0

beforeJune = D2(TF)

beforeJune = datetime
   15-Feb-2022 12:00:00

Compare duration Arrays

Create a duration array. One way to create it is to use the duration function to convert text that represents a length of time.

For example, convert text in hh:mm:ss format.

T1 = duration("03:37:12")

T1 = duration
   03:37:12

You can also convert numbers to duration arrays. The input numeric arrays represent hours, minutes, and seconds.

T2 = duration(0:2:6,30,0)

T2 = 1x4 duration
   00:30:00   02:30:00   04:30:00   06:30:00

Compare the two duration arrays. The result show which elements of T2 are longer than T1.

TF = T1 < T2

TF = 1x4 logical array

   0   0   1   1

To create a new duration array containing only the matching elements, index into T2 using TF.

longerThanT1 = T2(TF)

longerThanT1 = 1x2 duration
   04:30:00   06:30:00

Text and duration Arrays

If you have text that represents a length of time, and it is formatted in a way that the duration function recognizes, then you can compare the text to a duration array. The comparison implicitly converts the text.

For example, compare a string that represents two hours and five minutes to T2. The first element of T2 is shorter.

T2 >= "02:05:00"

ans = 1x4 logical array

   0   1   1   1

longerThan205 = T2(TF)

longerThan205 = 1x2 duration
   04:30:00   06:30:00

Numbers and duration Arrays

You can compare numeric arrays to duration arrays. The comparison treats a numeric value as a number of fixed-length (24-hour) days.

Compare the elements of T2 to one day. Every element is shorter.

TF = T2 < 1

TF = 1x4 logical array

   1   1   1   1

T2(TF)

ans = 1x4 duration
   00:30:00   02:30:00   04:30:00   06:30:00

Compare the elements of T2 to one hour. Only the first element of T2 is shorter.

TF = T2 < 1/24

TF = 1x4 logical array

   1   0   0   0

T2(TF)

ans = duration
   00:30:00

Comparisons Across Different Time Zones

Create datetime values for October 1, 2022, at 4:00 p.m. in Los Angeles and October 1, 2022 at 5:00 p.m. in New York. The two cities are so far apart that they are in different time zones.

You can create datetime arrays with time zones by specifying the TimeZone name-value argument. To show the time zone when displaying these values, specify the Format name-value argument. Note that you can specify a datetime display format that differs from the format of the input text.

LAtime = datetime("2022-10-01 16:00:00", ...
                  "TimeZone","America/Los_Angeles",...
                  "Format","dd-MMM-yyyy hh:mm:ss a z")

LAtime = datetime
   01-Oct-2022 04:00:00 PM PDT

NYtime = datetime("2022-10-01 17:00:00", ...
                  "TimeZone","America/New_York",...
                  "Format","dd-MMM-yyyy hh:mm:ss a z")

NYtime = datetime
   01-Oct-2022 05:00:00 PM EDT

Compare the times in the two cities. 4:00 p.m. in Los Angeles occurs after 5:00 p.m. on the same day in New York. When you specify time zones, comparisons of datetime arrays account for the time zone information of each array.

TF = NYtime < LAtime

TF = logical
   1

Other Comparisons

MATLAB provides other functions for date and time comparisons.

• isbetween — Determine if datetime or duration values are within an interval

• isdst — Determine if datetime values occur during daylight saving time

• isnat — Determine if datetime values are NaT (Not-a-Time) values

• isweekend — Determine if datetime values occur during a weekend (Saturday and Sunday)

For example, determine if any elements of a datetime array occur during the first quarter of 2022.

start1Q = datetime("2022-01-01");
end1Q = datetime("2022-04-01");
D = datetime(2022,2:4:10,15,12,0,0)

D = 1x3 datetime
   15-Feb-2022 12:00:00   15-Jun-2022 12:00:00   15-Oct-2022 12:00:00

TF = isbetween(D,start1Q,end1Q)

TF = 1x3 logical array

   1   0   0

Display the elements of D that occur during the first quarter.

D(TF)

ans = datetime
   15-Feb-2022 12:00:00

Specify the time zone of D by setting its TimeZone property. Then determine if any elements occur during daylight saving time.

D.TimeZone = "America/New_York";
isdst(D)

ans = 1x3 logical array

   0   1   1

Determine if any elements occur during a weekend.

isweekend(D)

ans = 1x3 logical array

   0   0   1

To show the day of the week of the matching elements, use the day function.

weekendDays = D(isweekend(D))

weekendDays = datetime
   15-Oct-2022 12:00:00

day(weekendDays,"name")

ans = 1x1 cell array
    {'Saturday'}