Python: Using .format() on a Unicode-escaped string

Question

I am using Python 2.6.5. My code requires the use of the “more than or equal to” sign. Here it goes:

>>> s = u'u2265'
>>> print s
>>> ≥
>>> print "{0}".format(s)
Traceback (most recent call last):
     File "<input>", line 1, in <module> 
UnicodeEncodeError: 'ascii' codec can't encode character u'u2265'
  in position 0: ordinal not in range(128)`

Why do I get this error? Is there a right way to do this? I need to use the .format() function.

Asked By: Kit

||

Source

Answer 1

Just make the second string also a unicode string

>>> s = u'u2265'
>>> print s
≥
>>> print "{0}".format(s)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
UnicodeEncodeError: 'ascii' codec can't encode character u'u2265' in position 0: ordinal not in range(128)
>>> print u"{0}".format(s)
≥
>>>

Answered By: Mad Scientist

Answer 2

unicodes need unicode format strings.

>>> print u'{0}'.format(s)
≥

Answered By: Ignacio Vazquez-Abrams

Answer 3

A bit more information on why that happens.

>>> s = u'u2265'
>>> print s

works because print automatically uses the system encoding for your environment, which was likely set to UTF-8. (You can check by doing import sys; print sys.stdout.encoding)

>>> print "{0}".format(s)

fails because format tries to match the encoding of the type that it is called on (I couldn’t find documentation on this, but this is the behavior I’ve noticed). Since string literals are byte strings encoded as ASCII in python 2, format tries to encode s as ASCII, which then results in that exception. Observe:

>>> s = u'u2265'
>>> s.encode('ascii')
Traceback (most recent call last):
  File "<input>", line 1, in <module>
UnicodeEncodeError: 'ascii' codec can't encode character u'u2265' in position 0: ordinal not in range(128)

So that is basically why these approaches work:

>>> s = u'u2265'
>>> print u'{}'.format(s)
≥
>>> print '{}'.format(s.encode('utf-8'))
≥

The source character set is defined by the encoding declaration; it is ASCII if no encoding declaration is given in the source file
(https://docs.python.org/2/reference/lexical_analysis.html#string-literals)

Answered By: lps

Python: Using .format() on a Unicode-escaped string

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