Python:从ISO-8859-1/latin1转换为UTF-8

Question

我有这个字符串已经使用电子邮件模块从Quoted-printable解码为ISO-8859-1.这给了我像"\ xC4pple"这样的字符串,它们对应于"Äpple"(Apple中的瑞典语).但是,我无法将这些字符串转换为UTF-8.

>>> apple = "\xC4pple"
>>> apple
'\xc4pple'
>>> apple.encode("UTF-8")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc4 in position 0: ordinal not in     range(128)

我该怎么办？

Answer 1

这是一个常见问题,所以这里有一个相对彻底的例子.

对于非unicode字符串(即那些没有u前缀的字符串u'\xc4pple'),必须从本机编码解码(iso8859-1/ latin1,除非用神秘sys.setdefaultencoding函数修改)unicode,然后编码为可以显示你想要的字符的字符集,在这种情况下我推荐UTF-8.

首先,这是一个方便的实用程序函数,它将有助于阐明Python 2.7字符串和unicode的模式:

>>> def tell_me_about(s): return (type(s), s)

简单的字符串

>>> v = "\xC4pple" # iso-8859-1 aka latin1 encoded string

>>> tell_me_about(v)
(<type 'str'>, '\xc4pple')

>>> v
'\xc4pple'        # representation in memory

>>> print v
?pple             # map the iso-8859-1 in-memory to iso-8859-1 chars
                  # note that '\xc4' has no representation in iso-8859-1, 
                  # so is printed as "?".

解码iso8859-1字符串 - 将纯字符串转换为unicode

>>> uv = v.decode("iso-8859-1")
>>> uv
u'\xc4pple'       # decoding iso-8859-1 becomes unicode, in memory

>>> tell_me_about(uv)
(<type 'unicode'>, u'\xc4pple')

>>> print v.decode("iso-8859-1")
Äpple             # convert unicode to the default character set
                  # (utf-8, based on sys.stdout.encoding)

>>> v.decode('iso-8859-1') == u'\xc4pple'
True              # one could have just used a unicode representation 
                  # from the start

再说一点 - 用"Ä"

>>> u"Ä" == u"\xc4"
True              # the native unicode char and escaped versions are the same

>>> "Ä" == u"\xc4"  
False             # the native unicode char is '\xc3\x84' in latin1

>>> "Ä".decode('utf8') == u"\xc4"
True              # one can decode the string to get unicode

>>> "Ä" == "\xc4"
False             # the native character and the escaped string are
                  # of course not equal ('\xc3\x84' != '\xc4').

编码为UTF

>>> u8 = v.decode("iso-8859-1").encode("utf-8")
>>> u8
'\xc3\x84pple'    # convert iso-8859-1 to unicode to utf-8

>>> tell_me_about(u8)
(<type 'str'>, '\xc3\x84pple')

>>> u16 = v.decode('iso-8859-1').encode('utf-16')
>>> tell_me_about(u16)
(<type 'str'>, '\xff\xfe\xc4\x00p\x00p\x00l\x00e\x00')

>>> tell_me_about(u8.decode('utf8'))
(<type 'unicode'>, u'\xc4pple')

>>> tell_me_about(u16.decode('utf16'))
(<type 'unicode'>, u'\xc4pple')

unicode与UTF和latin1之间的关系

>>> print u8
Äpple             # printing utf-8 - because of the encoding we now know
                  # how to print the characters

>>> print u8.decode('utf-8') # printing unicode
Äpple

>>> print u16     # printing 'bytes' of u16
???pple

>>> print u16.decode('utf16')
Äpple             # printing unicode

>>> v == u8
False             # v is a iso8859-1 string; u8 is a utf-8 string

>>> v.decode('iso8859-1') == u8
False             # v.decode(...) returns unicode

>>> u8.decode('utf-8') == v.decode('latin1') == u16.decode('utf-16')
True              # all decode to the same unicode memory representation
                  # (latin1 is iso-8859-1)

Unicode例外

 >>> u8.encode('iso8859-1')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 0:
  ordinal not in range(128)

>>> u16.encode('iso8859-1')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
UnicodeDecodeError: 'ascii' codec can't decode byte 0xff in position 0:
  ordinal not in range(128)

>>> v.encode('iso8859-1')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc4 in position 0:
  ordinal not in range(128)

通过从特定编码(latin-1,utf8,utf16)转换为unicode,可以解决这些问题u8.decode('utf8').encode('latin1').

所以也许人们可以得出以下原则和概括:

• type str是一组字节,可以有多种编码之一,如Latin-1,UTF-8和UTF-16
• type unicode是一组字节,可以转换为任意数量的编码,最常见的是UTF-8和latin-1(iso8859-1)
• 该print命令有自己的编码,设置sys.stdout.encoding和默认为UTF-8 的逻辑
• str在转换为另一种编码之前,必须将a解码为unicode.

当然,Python 3.x中的所有这些变化.

希望这很有启发性.

进一步阅读

• 字符与字节,由蒂姆布雷.

Armin Ronacher的非常具有说服力的咆哮:

• Python上的Unicode更新指南(2013年7月2日)
• 有关Python 2和3中的Unicode的更多信息(2014年1月5日)
• UCS与UTF-8作为内部字符串编码(2014年1月9日)
• 你不想在Python 3中了解Unicode的所有内容(2014年5月12日)

Answer 2

首先尝试解码,然后编码:

apple.decode('iso-8859-1').encode('utf8')

Answer 3

对于Python 3:

bytes(apple,'iso-8859-1').decode('utf-8')

我用这个文本错误地编码为iso-8859-1(显示像VeÅ\x99ejné的单词)而不是utf-8.此代码生成正确版本Veřejné.

Answer 4

解码为Unicode,将结果编码为UTF8.

apple.decode('latin1').encode('utf8')