Working with Time Series Data

Interval Functions INTNX and INTCK

The SAS interval functions INTNX and INTCK perform calculations with date, datetime values, and time intervals. They can be used for calendar calculations with SAS date values, to count time intervals between dates, and to increment dates or datetime values by intervals.

The INTNX function increments dates by intervals. INTNX computes the date or datetime of the start of the interval a specified number of intervals from the interval containing a given date or datetime value.

The form of the INTNX function is

INTNX( interval, from, n <, alignment > )

where:

interval: is a character constant or variable containing an interval name.
from: is a SAS date value (for date intervals) or datetime value (for datetime intervals).
n: is the number of intervals to increment from the interval containing the from value.
alignment: controls the alignment of SAS dates, within the interval, used to identify output observations. Can take the values BEGINNING|B, MIDDLE|M, or END|E.

The number of intervals to increment, n, can be positive, negative, or zero.

For example, the statement NEXTMON = INTNX('MONTH',DATE,1); assigns to the variable NEXTMON the date of the first day of the month following the month containing the value of DATE.

The INTCK function counts the number of interval boundaries between two dates or between two datetime values.

The form of the INTCK function is

INTCK( interval, from, to )

where:

interval: is a character constant or variable containing an interval name
from: is the starting date (for date intervals) or datetime value (for datetime intervals)
to: is the ending date (for date intervals) or datetime value (for datetime intervals).

For example, the statement NEWYEARS = INTCK('YEAR',DATE1,DATE2); assigns to the variable NEWYEARS the number of New Year's Days between the two dates.

Interval Functions INTNX and INTCK

Incrementing Dates by Intervals

Alignment of SAS Dates

Computing the Width of a Time Interval

Computing the Ceiling of an Interval

Counting Time Intervals

Checking Data Periodicity

Filling in Omitted Observations in a Time Series Data Set

Using Interval Functions for Calendar Calculations