6.5. "unicodedata" — Unicode Database
*************************************

======================================================================

This module provides access to the Unicode Character Database (UCD)
which defines character properties for all Unicode characters. The
data contained in this database is compiled from the UCD version
9.0.0.

The module uses the same names and symbols as defined by Unicode
Standard Annex #44, “Unicode Character Database”.  It defines the
following functions:

unicodedata.lookup(name)

   Look up character by name.  If a character with the given name is
   found, return the corresponding character.  If not found,
   "KeyError" is raised.

   Changed in version 3.3: Support for name aliases [1] and named
   sequences [2] has been added.

unicodedata.name(chr[, default])

   Returns the name assigned to the character *chr* as a string. If no
   name is defined, *default* is returned, or, if not given,
   "ValueError" is raised.

unicodedata.decimal(chr[, default])

   Returns the decimal value assigned to the character *chr* as
   integer. If no such value is defined, *default* is returned, or, if
   not given, "ValueError" is raised.

unicodedata.digit(chr[, default])

   Returns the digit value assigned to the character *chr* as integer.
   If no such value is defined, *default* is returned, or, if not
   given, "ValueError" is raised.

unicodedata.numeric(chr[, default])

   Returns the numeric value assigned to the character *chr* as float.
   If no such value is defined, *default* is returned, or, if not
   given, "ValueError" is raised.

unicodedata.category(chr)

   Returns the general category assigned to the character *chr* as
   string.

unicodedata.bidirectional(chr)

   Returns the bidirectional class assigned to the character *chr* as
   string. If no such value is defined, an empty string is returned.

unicodedata.combining(chr)

   Returns the canonical combining class assigned to the character
   *chr* as integer. Returns "0" if no combining class is defined.

unicodedata.east_asian_width(chr)

   Returns the east asian width assigned to the character *chr* as
   string.

unicodedata.mirrored(chr)

   Returns the mirrored property assigned to the character *chr* as
   integer. Returns "1" if the character has been identified as a
   “mirrored” character in bidirectional text, "0" otherwise.

unicodedata.decomposition(chr)

   Returns the character decomposition mapping assigned to the
   character *chr* as string. An empty string is returned in case no
   such mapping is defined.

unicodedata.normalize(form, unistr)

   Return the normal form *form* for the Unicode string *unistr*.
   Valid values for *form* are ‘NFC’, ‘NFKC’, ‘NFD’, and ‘NFKD’.

   The Unicode standard defines various normalization forms of a
   Unicode string, based on the definition of canonical equivalence
   and compatibility equivalence. In Unicode, several characters can
   be expressed in various way. For example, the character U+00C7
   (LATIN CAPITAL LETTER C WITH CEDILLA) can also be expressed as the
   sequence U+0043 (LATIN CAPITAL LETTER C) U+0327 (COMBINING
   CEDILLA).

   For each character, there are two normal forms: normal form C and
   normal form D. Normal form D (NFD) is also known as canonical
   decomposition, and translates each character into its decomposed
   form. Normal form C (NFC) first applies a canonical decomposition,
   then composes pre-combined characters again.

   In addition to these two forms, there are two additional normal
   forms based on compatibility equivalence. In Unicode, certain
   characters are supported which normally would be unified with other
   characters. For example, U+2160 (ROMAN NUMERAL ONE) is really the
   same thing as U+0049 (LATIN CAPITAL LETTER I). However, it is
   supported in Unicode for compatibility with existing character sets
   (e.g. gb2312).

   The normal form KD (NFKD) will apply the compatibility
   decomposition, i.e. replace all compatibility characters with their
   equivalents. The normal form KC (NFKC) first applies the
   compatibility decomposition, followed by the canonical composition.

   Even if two unicode strings are normalized and look the same to a
   human reader, if one has combining characters and the other
   doesn’t, they may not compare equal.

In addition, the module exposes the following constant:

unicodedata.unidata_version

   The version of the Unicode database used in this module.

unicodedata.ucd_3_2_0

   This is an object that has the same methods as the entire module,
   but uses the Unicode database version 3.2 instead, for applications
   that require this specific version of the Unicode database (such as
   IDNA).

Examples:

>>> import unicodedata
>>> unicodedata.lookup('LEFT CURLY BRACKET')
'{'
>>> unicodedata.name('/')
'SOLIDUS'
>>> unicodedata.decimal('9')
9
>>> unicodedata.decimal('a')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: not a decimal
>>> unicodedata.category('A')  # 'L'etter, 'u'ppercase
'Lu'
>>> unicodedata.bidirectional('\u0660') # 'A'rabic, 'N'umber
'AN'

-[ Footnotes ]-

[1] http://www.unicode.org/Public/9.0.0/ucd/NameAliases.txt

[2] http://www.unicode.org/Public/9.0.0/ucd/NamedSequences.txt
