datefix

Version 1.1.3 | 2026-10-26

Quick Start · Installation · Key Options · Version History · Stata-Tools · Report a bug

datefix converts imported string date variables to numeric Stata daily dates for users cleaning data after import. It can infer date order, preserve raw values in a new variable, apply %td display formats, and identify values that prevent conversion.

Quick Start

After installing, convert an imported day-month-year string in place:

clear
input str10 visit_date
"31/01/2020"
"15/02/2020"
"07/03/2020"
end

datefix visit_date
list

The command auto-detects the ordering and displays the converted variable with the default %tdCCYY/NN/DD format. More examples, including newvar(), topyear() and diagnose, are in help datefix.

Features

• Detects the date order. Without order(), datefix tries MDY, DMY and YMD and keeps the ordering with the most valid parses; order() fixes it when the input is ambiguous. Daily dates only: datetime strings fail conversion.
• All or nothing. A nonmissing string that fails to parse stops the command before any variable in the varlist is replaced, and an all-missing source stops with r(2000), so a failed or empty conversion is never reported as a success.
• Finds the bad values. diagnose lists each distinct unconvertible value with its frequency and observation numbers.
• Raw values kept on request. newvar() writes the date to a new variable and keeps the imported string (unless drop); df() changes only the display format. A numeric input is taken to hold daily dates already and is only formatted or copied.

Requirements

• Stata 16 or later

Installation

capture ado uninstall datefix
net install datefix, from("https://raw.githubusercontent.com/tpcopeland/Stata-Tools/main/datefix") replace

Commands

Command	Description
datefix	Convert string dates; format or copy existing numeric daily-date values

Key Options

Syntax: datefix varlist [, newvar(name) drop df(%fmt) order(string) topyear(#) diagnose]. Use one or more source variables; newvar() is limited to a single source variable, and order() accepts MDY, DMY, or YMD (case-insensitive).

Option	Default	Description
newvar(name)	Off	Create a new numeric date variable; retain the source unless drop is also specified
drop	Off	Drop the source variable when newvar() is used; without newvar(), it is redundant because strings are replaced and numeric inputs are formatted in place
df(%fmt)	%tdCCYY/NN/DD	Apply a Stata daily-date display format; the format must begin with %td
order(string)	Auto	Parse strings as MDY, DMY, or YMD; automatic detection chooses the most valid ordering, with MDY preferred for top-count ties and YMD preferred over DMY when those two tie above MDY
topyear(#)	Off	Pass an integer top-year argument to date() for two-digit years
diagnose	Off	On string-conversion failure, list unconvertible values, frequencies, and observation numbers; the option may be abbreviated to diag

Stored Results

datefix defines no stored results and clears incidental r() state before returning. Conversion messages, the auto-detected order (when order() is omitted), and missing-value counts are printed in the Results window.

QA

QA suites and how to run them are documented in qa/README.md.

Version History

• 1.1.3 (2026-10-13): The summary line for a numeric input now says the variable is already numeric and only had the date format applied, instead of claiming it was converted.
• 1.1.2 (2026-08-11): Accepted colon-separated daily dates, rejected all-missing inputs without mutation, preserved literal Unicode diagnostic values, and made help examples and the local-install demo self-contained.
• 1.1.1 (2026-08-05): Made multi-variable conversion atomic and cleared incidental r() state on return.

Earlier versions

• 1.1.0 (2026-06-25): Added the diagnose option, which reports distinct unconvertible values, their frequencies, and observation numbers when conversion fails.
• 1.0.1 (2026-06-19): Documentation fixes — df() and drop now render as options in the help file, added section markers, and standardized the author string.
• 1.0.0 (2026-04-08): Initial release with auto-detection, newvar(), custom display formats, and topyear() support.

Author

Timothy P Copeland, Karolinska Institutet

Questions and bug reports: GitHub issues. Please include the first line of which datefix and your Stata version.

To cite: Copeland TP. datefix: Imported date strings to Stata dates. Stata-Tools, https://github.com/tpcopeland/Stata-Tools/tree/main/datefix. Please give the version you used (which datefix prints it).

License

MIT (see LICENSE)