= Stata Data Formats =

The Stata data file format encodes variable metadata including '''display formats'''. While these formats primarily affect visualization, they can also encode critical information about how a variable should be used.

See also the underlying [[Stata/DataTypes|data types]].

<<TableOfContents>>

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== Display Formats ==

A display format is set like:

{{{
generate double my_datetime = clock(some_string, "YMDhms")
format my_datetime %tc
}}}

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=== Numeric Formats ===

For the most part, all numeric types operate the same way in Stata.

See [[Stata/NumericFunctions|Numeric Functions]] for operating on this type of data.

Each underlying numeric data format applies a different display format by default. They are:

||'''Type'''||'''Format'''||
||double    ||`%10.0g`    ||
||float     ||`%9.0g`     ||
||long      ||`%12.0g`    ||
||int       ||`%8.0g`     ||
||byte      ||`%8.0g`     ||

The available numeric formats are:

 * '''general format''' (`g`) indicating that the number of decimal places should be shifted to improve readability
 * '''fixed width format''' (`f`) indicating that a fixed number of decimal places should be shown
 * '''scientific format''' (`e`) indicating that scientific notation should be used

As an example:

||'''Value'''||'''With format `%9.4g`'''||'''With format `%9.4f`'''||'''With format `%9.2e`'''||
||3.14159    ||3.142                    ||3.14                     ||3.14e+00                 ||
||314.159    ||314.2                    ||314.16                   ||3.14e+02                 ||

A `c` can be appended to any numeric format to display commas.

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=== Date and Datetime Formats ===

Dates and datetimes are numeric data with a standardized, encoded meaning. The display format is what indicates the intended encoding. For the most part, this type of data counts days or milliseconds from the Stata epoch: `01jan1960 00:00:00.000`.

See [[Stata/DatetimeFunctions|Datetime Functions]] for operating on this type of data.

Specifically, the date and datetime formats are:

||'''Format''' ||'''Unit'''                               ||
||`%tc`        ||milliseconds '''ignoring''' leap seconds ||
||`%tC`        ||milliseconds '''with''' leap seconds     ||
||`%td`        ||days                                     ||
||`%tw`        ||weeks                                    ||
||`%tm`        ||months                                   ||
||`%tq`        ||quarters                                 ||
||`%th`        ||half-years                               ||
||`%ty`        ||years                                    ||

These formats can be further customized, for visualization purposes only, with specific components.

||'''Component'''  ||'''Specification'''||'''Displays As'''              ||
||Century          ||`CC`               ||`01`-`99`                      ||
||Century          ||`cc`               ||`1`-`99`                       ||
||Year             ||`YY`               ||`01`-`99`                      ||
||Year             ||`yy`               ||`1`-`99`                       ||
||Day of year      ||`JJJ`              ||`001`-`366`                    ||
||Day of year      ||`jjj`              ||`1`-`366`                      ||
||Month            ||`Mon`              ||`Jan`-`Dec`                    ||
||Month            ||`Month`            ||`January`-`December`           ||
||Month            ||`mon`              ||`jan`-`dec`                    ||
||Month            ||`month`            ||`january`-`december`           ||
||Month            ||`NN`               ||`01`-`12`                      ||
||Month            ||`nn`               ||`1`-`12`                       ||
||Day              ||`DD`               ||`01`-`31`                      ||
||Day              ||`dd`               ||`1`-`31`                       ||
||Day of week      ||`DAYNAME`          ||`Sunday`-`Saturday` (aligned)  ||
||Day of week      ||`Dayname`          ||`Sunday`-`Saturday` (unaligned)||
||Day of week      ||`Day`              ||`Sun`-`Sat`                    ||
||Day of week      ||`Da`               ||`Su`-`Sa`                      ||
||Day of week      ||`day`              ||`sun`-`sat`                    ||
||Day of week      ||`da`               ||`su`-`sa`                      ||
||Half-year        ||`h`                ||`1` or `2`                     ||
||Quarter          ||`q`                ||`1`-`4`                        ||
||Week             ||`WW`               ||`01`-`52`                      ||
||Week             ||`ww`               ||`1`-`52`                       ||
||Hour             ||`HH`               ||`00`-`23`                      ||
||Hour             ||`Hh`               ||`00`-`12`                      ||
||Hour             ||`hH`               ||`0`-`23`                       ||
||Hour             ||`hh`               ||`0`-`12`                       ||
||Minute           ||`MM`               ||`00`-`59`                      ||
||Minute           ||`mm`               ||`0`-`59`                       ||
||Second           ||`SS`               ||`00`-`60` (due to leap second) ||
||Second           ||`ss`               ||`0`-`60` (due to leap second)  ||
||Tenths           ||`.s`               ||`.0`-`.9`                      ||
||Hundredths       ||`.ss`              ||`.00`-`.99`                    ||
||Thousandths      ||`.sss`             ||`.000`-`.999`                  ||
||AM/PM            ||`am`/`pm`          ||`am` or `pm`                   ||
||AM/PM            ||`a.m.`/`p.m.`      ||`a.m.` or `p.m.`               ||
||AM/PM            ||`AM`/`PM`          ||`AM` or `PM`                   ||
||AM/PM            ||`A.M.`/`P.M.`      ||`A.M.` or `P.M.`               ||
||Period           ||`.`                ||`.`                            ||
||Comma            ||`,`                ||`,`                            ||
||Colon            ||`:`                ||`:`                            ||
||Hyphen           ||`-`                ||`-`                            ||
||Space            ||` `                ||` `                            ||
||Forward slash    ||`/`                ||`/`                            ||
||Back slash       ||`\`                ||`\`                            ||
||Literal character||`!c`               ||`c`                            ||

A plus sign (`+`) can optionally delimit components for human readability. It is ignored otherwise.

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=== String Formats ===

Alignment is controlled by the presence or absence of a negative sign (`-`) ahead of the width. A string variable formatted as `%-18s` will be left-justified; with a format of `%18s` it would have been right-justified.

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== See also ==

[[https://www.stata.com/manuals/ddatetime.pdf|Stata datetimes]]



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