Stata Datetime Functions

Stata supports these datetime functions in the global scope.

Functions Converting Integers

Functions Converting a String

These functions convert a string into a numeric value that represents a date or time. Masks instruct how a date or time as represented in string data. A datetime format still must be separately applied to the numeric value.

As an example, the mask of "DMY" can parse all of:

• "21nov2006"

• "21 November 2006"

• "21-11-2006"

• "21112006"

Spaces are ignored in a mask; "DMY" is equivalent to "D M Y".

The mask "DMY" cannot parse a string with a two-digit year. A two-digit prefix can be applied to "Y" in the mask, such as "DM19Y". If a string has a two-digit year, such a mask will cause the year to be interpreted as being within the 1900s. If a string has a four-digit year, the mask will not mutate the value.

Clock

Convert a string date and time into the number of milliseconds since the Stata epoch (01jan1960 00:00:00.000).

There are two functions: clock and Clock.

To create a datetime that ignores leap seconds, try:

generate double datetime = clock(string, "YMDhms")
format datetime %tc 

To create a datetime that includes leap seconds since the epoch, try:

generate double datetime = Clock(string, "YMDhms")
format datetime %tC 

As noted above, the mask should be composed of: "Y", "M", "D", "h", "m", and "s".

Date

Convert a string date into the number of days since the Stata epoch (01jan1960 00:00:00.000).

generate long date = date(string, "MDY")
format date %td

As noted above, the mask should be composed of: "Y", "M", and "D". See above for details on masks.

HalfYearly

Convert a string date into the number of half years since the Stata epoch (01jan1960 00:00:00.000).

generate int halfyear = halfyearly(string, "YH")
format halfyear %th

As noted above, the mask should be composed of: "Y" and "H". See above for details on masks.

Monthly

Convert a string like "2012m12" into the number of months since the Stata epoch (01jan1960 00:00:00.000).

generate int month = monthly(string, "YM")
format month %tm

As noted above, the mask should be composed of: "Y" and "M". See above for details on masks.

If a string is instead formatted like "201212" or "2000-12", try:

generate int month = mofd(date(string, "YM"))
format month %tm

Quarterly

Convert a string like "2012q4" into the number of quarters since the Stata epoch (01jan1960 00:00:00.000).

generate int quarter = quarterly(string, "YQ")
format quarter %tq

As noted above, the mask should be composed of: "Y" and "Q". See above for details on masks.

Weekly

Convert a string date into the number of weeks since the Stata epoch (01jan1960 00:00:00.000).

generate int week = weekly(string, "YW")
format week %tw

As noted above, the mask should be composed of: "Y" and "W". See above for details on masks.

Yearly

Convert a string date into the number of years since the Stata epoch (01jan1960 00:00:00.000).

generate int year = yearly(string, "Y")
format year %ty

As noted above, the mask should be composed of: "Y" and "W". See above for details on masks.

Datetime Functions

These functions should only be used on numeric variables with a date or datetime format.

COfC

Convert a datetime around the handling of leap seconds.

Cofc takes a datetime ignoring leap seconds since the Stata epoch (01jan1960 00:00:00.000) as input, and returns a datetime including them.

cofC does the reverse.

generate double datetime2 = cofC(datetime)
format datetime2 %tc

generate double datetime3 = Cofc(datetime)
format datetime3 %tC

COfD

Convert a date into a datetime.

There are two functions: cofd and Cofd. They return a numeric value that should be formatted as %tc or %tC, respectively.

generate double datetime = cofd(date)
format datetime %tc

generate double datetime2 = Cofd(date)
format datetime2 %tC

Day

Extract the day of the month number (1 to 31) from a date (i.e. %td-formatted value).

generate byte day = day(date)

DOfC

Convert a datetime into a date.

There are two functions: dofc and dofC. They take a numeric value as input, formatted as %tc or %tC respectively.

generate long date = dofc(datetime)
#or
generate long date = dofC(datetime)

format date %td

DOfH

Convert a half-year (i.e. a %th-formatted value) into a date.

generate long date = dofh(halfyear)
format date %td

DOfM

Convert a month (i.e. a %tm-formatted value) into a date.

generate long date = dofm(month)
format date %td

DOfQ

Convert a quarter (i.e. a %tq-formatted value) into a date.

generate long date = dofq(quarter)
format date %td

DOfW

Convert a week (i.e. a %tw-formatted value) into a date.

generate long date = dofw(week)
format date %td

DOfY

Convert a year (i.e. a %ty-formatted value) into a date.

generate long date = dofy(year)
format date %td

Dow

Extract the day of the week number (0 to 6; Sunday is 0) from a date (i.e. %td-formatted value).

generate byte day = dow(date)

Doy

Extract the day of the year number (1 to 366) from a date (i.e. %td-formatted value).

generate byte day = doy(date)

HalfYear

Extract the half year number (1 to 2) from a date (i.e. %td-formatted value).

generate byte halfyear = halfyear(date)

HOfD

Convert a date (i.e. a %td-formatted value) into the number of half years since the Stata epoch (01jan1960 00:00:00.000).

generate int halfyears = hofd(date)
format halfyears %th

Hh

Extract the hours from a %tc-formatted datetime.

generate byte hours =hh(datetime)

HhC

Extract the hours from a %tC-formatted datetime.

generate byte hours =hhC(datetime)

Mm

Extract the minutes from a %tc-formatted datetime.

generate byte minutes = mm(datetime)

MmC

Extract the minutes from a %tC-formatted datetime.

generate byte minutes = mmC(datetime)

MOfD

Convert a date (i.e. a %td-formatted value) into the number of months since the Stata epoch (01jan1960 00:00:00.000).

generate int months = mofd(date)
format months %tm

Month

Extract the month number (1 to 12) from a date (i.e. %td-formatted value).

generate byte month = month(date)

QOfD

Convert a date (i.e. a %td-formatted value) into the number of quarters since the Stata epoch (01jan1960 00:00:00.000).

generate int quarters = qofd(date)
format quarters %tq

Quarter

Extract the quarter number (1 to 4) from a date (i.e. %td-formatted value).

generate byte quarter = quarter(date)

Ss

Extract the seconds from a %tc-formatted datetime.

generate byte seconds = ss(datetime)

SsC

Extract the seconds from a %tC-formatted datetime.

generate byte seconds = ssC(datetime)

Week

Extract the week number (1 to 52) from a date (i.e. %td-formatted value).

generate byte week = week(date)

WOfD

Convert a date (i.e. a %td-formatted value) into the number of weeks since the Stata epoch (01jan1960 00:00:00.000).

generate int weeks = wofd(date)
format weeks %tw

Year

Extract the year from a date (i.e. %td-formatted value).

generate byte year = year(date)

YOfD

Convert a date (i.e. a %td-formatted value) into the number of years since the Stata epoch (01jan1960 00:00:00.000).

generate int years = yofd(date)
format years %ty

CategoryRicottone