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/Doc/library/unicodedata.rst

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  1
  2:mod:`unicodedata` --- Unicode Database
  3=======================================
  4
  5.. module:: unicodedata
  6   :synopsis: Access the Unicode Database.
  7.. moduleauthor:: Marc-Andre Lemburg <mal@lemburg.com>
  8.. sectionauthor:: Marc-Andre Lemburg <mal@lemburg.com>
  9.. sectionauthor:: Martin v. Lรถwis <martin@v.loewis.de>
 10
 11
 12.. index::
 13   single: Unicode
 14   single: character
 15   pair: Unicode; database
 16
 17This module provides access to the Unicode Character Database which defines
 18character properties for all Unicode characters. The data in this database is
 19based on the :file:`UnicodeData.txt` file version 5.1.0 which is publicly
 20available from ftp://ftp.unicode.org/.
 21
 22The module uses the same names and symbols as defined by the UnicodeData File
 23Format 5.1.0 (see http://www.unicode.org/Public/5.1.0/ucd/UCD.html).  It defines
 24the following functions:
 25
 26
 27.. function:: lookup(name)
 28
 29   Look up character by name.  If a character with the given name is found, return
 30   the corresponding Unicode character.  If not found, :exc:`KeyError` is raised.
 31
 32
 33.. function:: name(unichr[, default])
 34
 35   Returns the name assigned to the Unicode character *unichr* as a string. If no
 36   name is defined, *default* is returned, or, if not given, :exc:`ValueError` is
 37   raised.
 38
 39
 40.. function:: decimal(unichr[, default])
 41
 42   Returns the decimal value assigned to the Unicode character *unichr* as integer.
 43   If no such value is defined, *default* is returned, or, if not given,
 44   :exc:`ValueError` is raised.
 45
 46
 47.. function:: digit(unichr[, default])
 48
 49   Returns the digit value assigned to the Unicode character *unichr* as integer.
 50   If no such value is defined, *default* is returned, or, if not given,
 51   :exc:`ValueError` is raised.
 52
 53
 54.. function:: numeric(unichr[, default])
 55
 56   Returns the numeric value assigned to the Unicode character *unichr* as float.
 57   If no such value is defined, *default* is returned, or, if not given,
 58   :exc:`ValueError` is raised.
 59
 60
 61.. function:: category(unichr)
 62
 63   Returns the general category assigned to the Unicode character *unichr* as
 64   string.
 65
 66
 67.. function:: bidirectional(unichr)
 68
 69   Returns the bidirectional category assigned to the Unicode character *unichr* as
 70   string. If no such value is defined, an empty string is returned.
 71
 72
 73.. function:: combining(unichr)
 74
 75   Returns the canonical combining class assigned to the Unicode character *unichr*
 76   as integer. Returns ``0`` if no combining class is defined.
 77
 78
 79.. function:: east_asian_width(unichr)
 80
 81   Returns the east asian width assigned to the Unicode character *unichr* as
 82   string.
 83
 84   .. versionadded:: 2.4
 85
 86
 87.. function:: mirrored(unichr)
 88
 89   Returns the mirrored property assigned to the Unicode character *unichr* as
 90   integer. Returns ``1`` if the character has been identified as a "mirrored"
 91   character in bidirectional text, ``0`` otherwise.
 92
 93
 94.. function:: decomposition(unichr)
 95
 96   Returns the character decomposition mapping assigned to the Unicode character
 97   *unichr* as string. An empty string is returned in case no such mapping is
 98   defined.
 99
100
101.. function:: normalize(form, unistr)
102
103   Return the normal form *form* for the Unicode string *unistr*. Valid values for
104   *form* are 'NFC', 'NFKC', 'NFD', and 'NFKD'.
105
106   The Unicode standard defines various normalization forms of a Unicode string,
107   based on the definition of canonical equivalence and compatibility equivalence.
108   In Unicode, several characters can be expressed in various way. For example, the
109   character U+00C7 (LATIN CAPITAL LETTER C WITH CEDILLA) can also be expressed as
110   the sequence U+0327 (COMBINING CEDILLA) U+0043 (LATIN CAPITAL LETTER C).
111
112   For each character, there are two normal forms: normal form C and normal form D.
113   Normal form D (NFD) is also known as canonical decomposition, and translates
114   each character into its decomposed form. Normal form C (NFC) first applies a
115   canonical decomposition, then composes pre-combined characters again.
116
117   In addition to these two forms, there are two additional normal forms based on
118   compatibility equivalence. In Unicode, certain characters are supported which
119   normally would be unified with other characters. For example, U+2160 (ROMAN
120   NUMERAL ONE) is really the same thing as U+0049 (LATIN CAPITAL LETTER I).
121   However, it is supported in Unicode for compatibility with existing character
122   sets (e.g. gb2312).
123
124   The normal form KD (NFKD) will apply the compatibility decomposition, i.e.
125   replace all compatibility characters with their equivalents. The normal form KC
126   (NFKC) first applies the compatibility decomposition, followed by the canonical
127   composition.
128
129   Even if two unicode strings are normalized and look the same to
130   a human reader, if one has combining characters and the other
131   doesn't, they may not compare equal.
132
133   .. versionadded:: 2.3
134
135In addition, the module exposes the following constant:
136
137
138.. data:: unidata_version
139
140   The version of the Unicode database used in this module.
141
142   .. versionadded:: 2.3
143
144
145.. data:: ucd_3_2_0
146
147   This is an object that has the same methods as the entire module, but uses the
148   Unicode database version 3.2 instead, for applications that require this
149   specific version of the Unicode database (such as IDNA).
150
151   .. versionadded:: 2.5
152
153Examples:
154
155   >>> import unicodedata
156   >>> unicodedata.lookup('LEFT CURLY BRACKET')
157   u'{'
158   >>> unicodedata.name(u'/')
159   'SOLIDUS'
160   >>> unicodedata.decimal(u'9')
161   9
162   >>> unicodedata.decimal(u'a')
163   Traceback (most recent call last):
164     File "<stdin>", line 1, in ?
165   ValueError: not a decimal
166   >>> unicodedata.category(u'A')  # 'L'etter, 'u'ppercase
167   'Lu'
168   >>> unicodedata.bidirectional(u'\u0660') # 'A'rabic, 'N'umber
169   'AN'
170