1:mod:`unicodedata` --- Unicode Database
2=======================================
3
4.. module:: unicodedata
5   :synopsis: Access the Unicode Database.
6
7.. moduleauthor:: Marc-André Lemburg <mal@lemburg.com>
8.. sectionauthor:: Marc-André Lemburg <mal@lemburg.com>
9.. sectionauthor:: Martin v. Löwis <martin@v.loewis.de>
10
11.. index::
12   single: Unicode
13   single: character
14   pair: Unicode; database
15
16--------------
17
18This module provides access to the Unicode Character Database (UCD) which
19defines character properties for all Unicode characters. The data contained in
20this database is compiled from the `UCD version 13.0.0
21<https://www.unicode.org/Public/13.0.0/ucd>`_.
22
23The module uses the same names and symbols as defined by Unicode
24Standard Annex #44, `"Unicode Character Database"
25<https://www.unicode.org/reports/tr44/>`_.  It defines the
26following functions:
27
28
29.. function:: lookup(name)
30
31   Look up character by name.  If a character with the given name is found, return
32   the corresponding character.  If not found, :exc:`KeyError` is raised.
33
34   .. versionchanged:: 3.3
35      Support for name aliases [#]_ and named sequences [#]_ has been added.
36
37
38.. function:: name(chr[, default])
39
40   Returns the name assigned to the character *chr* as a string. If no
41   name is defined, *default* is returned, or, if not given, :exc:`ValueError` is
42   raised.
43
44
45.. function:: decimal(chr[, default])
46
47   Returns the decimal value assigned to the character *chr* as integer.
48   If no such value is defined, *default* is returned, or, if not given,
49   :exc:`ValueError` is raised.
50
51
52.. function:: digit(chr[, default])
53
54   Returns the digit value assigned to the character *chr* as integer.
55   If no such value is defined, *default* is returned, or, if not given,
56   :exc:`ValueError` is raised.
57
58
59.. function:: numeric(chr[, default])
60
61   Returns the numeric value assigned to the character *chr* as float.
62   If no such value is defined, *default* is returned, or, if not given,
63   :exc:`ValueError` is raised.
64
65
66.. function:: category(chr)
67
68   Returns the general category assigned to the character *chr* as
69   string.
70
71
72.. function:: bidirectional(chr)
73
74   Returns the bidirectional class assigned to the character *chr* as
75   string. If no such value is defined, an empty string is returned.
76
77
78.. function:: combining(chr)
79
80   Returns the canonical combining class assigned to the character *chr*
81   as integer. Returns ``0`` if no combining class is defined.
82
83
84.. function:: east_asian_width(chr)
85
86   Returns the east asian width assigned to the character *chr* as
87   string.
88
89
90.. function:: mirrored(chr)
91
92   Returns the mirrored property assigned to the character *chr* as
93   integer. Returns ``1`` if the character has been identified as a "mirrored"
94   character in bidirectional text, ``0`` otherwise.
95
96
97.. function:: decomposition(chr)
98
99   Returns the character decomposition mapping assigned to the character
100   *chr* as string. An empty string is returned in case no such mapping is
101   defined.
102
103
104.. function:: normalize(form, unistr)
105
106   Return the normal form *form* for the Unicode string *unistr*. Valid values for
107   *form* are 'NFC', 'NFKC', 'NFD', and 'NFKD'.
108
109   The Unicode standard defines various normalization forms of a Unicode string,
110   based on the definition of canonical equivalence and compatibility equivalence.
111   In Unicode, several characters can be expressed in various way. For example, the
112   character U+00C7 (LATIN CAPITAL LETTER C WITH CEDILLA) can also be expressed as
113   the sequence U+0043 (LATIN CAPITAL LETTER C) U+0327 (COMBINING CEDILLA).
114
115   For each character, there are two normal forms: normal form C and normal form D.
116   Normal form D (NFD) is also known as canonical decomposition, and translates
117   each character into its decomposed form. Normal form C (NFC) first applies a
118   canonical decomposition, then composes pre-combined characters again.
119
120   In addition to these two forms, there are two additional normal forms based on
121   compatibility equivalence. In Unicode, certain characters are supported which
122   normally would be unified with other characters. For example, U+2160 (ROMAN
123   NUMERAL ONE) is really the same thing as U+0049 (LATIN CAPITAL LETTER I).
124   However, it is supported in Unicode for compatibility with existing character
125   sets (e.g. gb2312).
126
127   The normal form KD (NFKD) will apply the compatibility decomposition, i.e.
128   replace all compatibility characters with their equivalents. The normal form KC
129   (NFKC) first applies the compatibility decomposition, followed by the canonical
130   composition.
131
132   Even if two unicode strings are normalized and look the same to
133   a human reader, if one has combining characters and the other
134   doesn't, they may not compare equal.
135
136.. function:: is_normalized(form, unistr)
137
138   Return whether the Unicode string *unistr* is in the normal form *form*. Valid
139   values for *form* are 'NFC', 'NFKC', 'NFD', and 'NFKD'.
140
141   .. versionadded:: 3.8
142
143
144In addition, the module exposes the following constant:
145
146.. data:: unidata_version
147
148   The version of the Unicode database used in this module.
149
150
151.. data:: ucd_3_2_0
152
153   This is an object that has the same methods as the entire module, but uses the
154   Unicode database version 3.2 instead, for applications that require this
155   specific version of the Unicode database (such as IDNA).
156
157Examples:
158
159   >>> import unicodedata
160   >>> unicodedata.lookup('LEFT CURLY BRACKET')
161   '{'
162   >>> unicodedata.name('/')
163   'SOLIDUS'
164   >>> unicodedata.decimal('9')
165   9
166   >>> unicodedata.decimal('a')
167   Traceback (most recent call last):
168     File "<stdin>", line 1, in <module>
169   ValueError: not a decimal
170   >>> unicodedata.category('A')  # 'L'etter, 'u'ppercase
171   'Lu'
172   >>> unicodedata.bidirectional('\u0660') # 'A'rabic, 'N'umber
173   'AN'
174
175
176.. rubric:: Footnotes
177
178.. [#] https://www.unicode.org/Public/13.0.0/ucd/NameAliases.txt
179
180.. [#] https://www.unicode.org/Public/13.0.0/ucd/NamedSequences.txt
181