This library is mainly for CLI programs that carefully produce output for Terminals, or make pretend to be an emulator.
Problem Statement: The printable length of most strings are equal to the
number of cells they occupy on the screen
1 character : 1 cell. However,
there are categories of characters that occupy 2 cells (full-wide), and
others that occupy 0 cells (zero-width).
Solution: POSIX.1-2001 and POSIX.1-2008 conforming systems provide wcwidth(3) and wcswidth(3) C functions of which this python module's functions precisely copy. These functions return the number of cells a unicode string is expected to occupy.
The stable version of this package is maintained on pypi, install using pip:
pip install wcwidth
Problem: given the following phrase (Japanese),
>>> text = u'コンニチハ'
Python incorrectly uses the string length of 5 codepoints rather than the printible length of 10 cells, so that when using the rjust function, the output length is wrong:
>>> print(len('コンニチハ')) 5 >>> print('コンニチハ'.rjust(20, '_')) _______________コンニチハ
By defining our own "rjust" function that uses wcwidth, we can correct this:
>>> def wc_rjust(text, length, padding=' '): ... from wcwidth import wcswidth ... return padding * max(0, (length - wcswidth(text))) + text ...
Our Solution uses wcswidth to determine the string length correctly:
>>> from wcwidth import wcswidth >>> print(wcswidth('コンニチハ')) 10 >>> print(wc_rjust('コンニチハ', 20, '_')) __________コンニチハ
Choosing a Version
Export an environment variable,
UNICODE_VERSION. This should be done by
terminal emulators or those developers experimenting with authoring one of
their own, from shell:
$ export UNICODE_VERSION=13.0
If unspecified, the latest version is used. If your Terminal Emulator does not export this variable, you can use the jquast/ucs-detect utility to automatically detect and export it to your shell.
wcwidth() to determine the length of a single unicode
wcswidth() to determine the length of many, a string
of unicode characters.
Briefly, return values of function
- Indeterminate (not printable).
- Does not advance the cursor, such as NULL or Combining.
- Characters of category East Asian Wide (W) or East Asian Full-width (F) which are displayed using two terminal cells.
- All others.
wcswidth() simply returns the sum of all values for each character
along a string, or
-1 when it occurs anywhere along a string.
Full API Documentation at https://wcwidth.readthedocs.org
Install wcwidth in editable mode:
pip install -e .
Execute unit tests using tox:
tox -e py27,py35,py36,py37,py38,py39,py310,py311,py312
Updating Unicode Version
Regenerate python code tables from latest Unicode Specification data files:
tox -e update
The script is located at
bin/update-tables.py, requires Python 3.9 or
later. It is recommended but not necessary to run this script with the newest
Python, because the newest Python has the latest
unicodedata for generating
This project is using sphinx 4.5 to build documentation:
tox -e sphinx
The output will be in
This project is using pip-tools to manage requirements.
To upgrade requirements for updating unicode version, run:
tox -e update_requirements_update
To upgrade requirements for testing, run:
tox -e update_requirements37,update_requirements39
To upgrade requirements for building documentation, run:
tox -e update_requirements_docs
Supplementary tools for browsing and testing terminals for wide unicode
characters are found in the bin/ of this project's source code. Just ensure
pip install -r requirements-develop.txt from this projects main
folder. For example, an interactive browser for testing:
This library is used in:
- jquast/blessed: a thin, practical wrapper around terminal capabilities in Python.
- prompt-toolkit/python-prompt-toolkit: a Library for building powerful interactive command lines in Python.
- dbcli/pgcli: Postgres CLI with autocompletion and syntax highlighting.
- thomasballinger/curtsies: a Curses-like terminal wrapper with a display based on compositing 2d arrays of text.
- selectel/pyte: Simple VTXXX-compatible linux terminal emulator.
- astanin/python-tabulate: Pretty-print tabular data in Python, a library and a command-line utility.
- rspeer/python-ftfy: Fixes mojibake and other glitches in Unicode text.
- nbedos/termtosvg: Terminal recorder that renders sessions as SVG animations.
- peterbrittain/asciimatics: Package to help people create full-screen text UIs.
- python-cmd2/cmd2: A tool for building interactive command line apps
- stratis-storage/stratis-cli: CLI for the Stratis project
- ihabunek/toot: A Mastodon CLI/TUI client
- saulpw/visidata: Terminal spreadsheet multitool for discovering and arranging data
- janlelis/unicode-display_width: Ruby
- alecrabbit/php-wcwidth: PHP
- Text::CharWidth: Perl
- bluebear94/Terminal-WCWidth: Perl 6
- mattn/go-runewidth: Go
- grepsuzette/wcwidth: Haxe
- aperezdc/lua-wcwidth: Lua
- joachimschmidt557/zig-wcwidth: Zig
- fumiyas/wcwidth-cjk: LD_PRELOAD override
- joshuarubin/wcwidth9: Unicode version 9 in C
- 0.2.12 2023-11-21
- re-release to remove .pyi file misplaced in wheel files Issue #101.
- 0.2.11 2023-11-20
- 0.2.10 2023-11-13
- 0.2.9 2023-10-30
- 0.2.8 2023-09-30
- Include requirements files in the source distribution (PR #82).
- 0.2.7 2023-09-28
- Updated tables to include Unicode Specification 15.1.0.
tox.iniin the source distribution
- 0.2.6 2023-01-14
- Updated tables to include Unicode Specification 14.0.0 and 15.0.0.
- Changed developer tools to use pip-compile, and to use jinja2 templates for code generation in bin/update-tables.py to prepare for possible compiler optimization release.
- 0.2.1 .. 0.2.5 2020-06-23
- Repository changes to update tests and packaging issues, and begin tagging repository with matching release versions.
- 0.2.0 2020-06-01
Enhancement: Unicode version may be selected by exporting the
UNICODE_VERSION, such as
6.3.0. See the jquast/ucs-detect CLI utility for automatic detection.
- Enhancement: API Documentation is published to readthedocs.org.
- Updated tables for all Unicode Specifications with files published in a programmatically consumable format, versions 4.1.0 through 13.0
- Enhancement: Unicode version may be selected by exporting the Environment variable
- 0.1.9 2020-03-22
- 0.1.8 2020-01-01
- Updated tables to Unicode Specification 12.0.0. (PR #30).
- 0.1.7 2016-07-01
- Updated tables to Unicode Specification 9.0.0. (PR #18).
- 0.1.6 2016-01-08 Production/Stable
LICENSEfile now included with distribution.
- 0.1.5 2015-09-13 Alpha
- Bugfix: Resolution of "combining character width" issue, most especially those that previously returned -1 now often (correctly) return 0. resolved by Philip Craig via PR #11.
The module path
wcwidth.table_combis no longer available, it has been superseded by module path
- 0.1.4 2014-11-20 Pre-Alpha
wcswidth()now determines printable length for (most) combining characters. The developer's tool bin/wcwidth-browser.py is improved to display combining characters when provided the
--combiningoption (Thomas Ballinger and Leta Montopoli PR #5).
- Feature: added static analysis (prospector) to testing framework.
- 0.1.3 2014-10-29 Pre-Alpha
- 0.1.2 2014-10-28 Pre-Alpha
- 0.1.1 2014-05-14 Pre-Alpha
- Initial release to pypi, Based on Unicode Specification 6.3.0
This code was originally derived directly from C code of the same name, whose latest version is available at https://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c:
* Markus Kuhn -- 2007-05-26 (Unicode 5.0) * * Permission to use, copy, modify, and distribute this software * for any purpose and without fee is hereby granted. The author * disclaims all warranties with regard to this software.