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Groups > comp.lang.python > #22301

Re: "convert" string to bytes without changing data (encoding)

Date 2012-03-28 11:17 -0700
From Ethan Furman <ethan@stoneleaf.us>
Subject Re: "convert" string to bytes without changing data (encoding)
References <9tg21lFmo3U1@mid.dfncis.de> <mailman.1065.1332925364.3037.python-list@python.org> <9tg4qoFbfpU1@mid.dfncis.de> <mailman.1069.1332931371.3037.python-list@python.org> <9th0u8Fuf2U1@mid.dfncis.de>
Newsgroups comp.lang.python
Message-ID <mailman.1090.1332959710.3037.python-list@python.org> (permalink)

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Peter Daum wrote:
> On 2012-03-28 12:42, Heiko Wundram wrote:
>> Am 28.03.2012 11:43, schrieb Peter Daum:
>>> ... in my example, the variable s points to a "string", i.e. a series of
>>> bytes, (0x61,0x62 ...) interpreted as ascii/unicode characters.
>> No; a string contains a series of codepoints from the unicode plane,
>> representing natural language characters (at least in the simplistic
>> view, I'm not talking about surrogates). These can be encoded to
>> different binary storage representations, of which ascii is (a common) one.
>>
>>> What I am looking for is a general way to just copy the raw data
>>> from a "string" object to a "byte" object without any attempt to
>>> "decode" or "encode" anything ...
>> There is "logically" no raw data in the string, just a series of
>> codepoints, as stated above. You'll have to specify the encoding to use
>> to get at "raw" data, and from what I gather you're interested in the
>> latin-1 (or iso-8859-15) encoding, as you're specifically referencing
>> chars >= 0x80 (which hints at your mindset being in LATIN-land, so to
>> speak).
> 
> The longer story of my question is: I am new to python (obviously), and
> since I am not familiar with either one, I thought it would be advisory
> to go for python 3.x. The biggest problem that I am facing is, that I
> am often dealing with data, that is basically text, but it can contain
> 8-bit bytes. In this case, I can not safely assume any given encoding,
> but I actually also don't need to know - for my purposes, it would be
> perfectly good enough to deal with the ascii portions and keep anything
> else unchanged.

Where is the data coming from?  Files?  In that case, it sounds like you 
will want to decode/encode using 'latin-1', as the bulk of your text is 
plain ascii and you don't really care about the upper-ascii chars.

~Ethan~

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Thread

"convert" string to bytes without changing data (encoding) Peter Daum <gator@cs.tu-berlin.de> - 2012-03-28 10:56 +0200
  Re: "convert" string to bytes without changing data (encoding) Chris Angelico <rosuav@gmail.com> - 2012-03-28 20:02 +1100
    Re: "convert" string to bytes without changing data (encoding) Peter Daum <gator@cs.tu-berlin.de> - 2012-03-28 11:43 +0200
      Re: "convert" string to bytes without changing data (encoding) Heiko Wundram <modelnine@modelnine.org> - 2012-03-28 12:42 +0200
        Re: "convert" string to bytes without changing data (encoding) Peter Daum <gator@cs.tu-berlin.de> - 2012-03-28 19:43 +0200
          Re: "convert" string to bytes without changing data (encoding) Heiko Wundram <modelnine@modelnine.org> - 2012-03-28 20:13 +0200
          Re: "convert" string to bytes without changing data (encoding) Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2012-03-28 21:13 +0300
            RE: "convert" string to bytes without changing data (encoding) "Prasad, Ramit" <ramit.prasad@jpmorgan.com> - 2012-03-28 18:31 +0000
            Re: "convert" string to bytes without changing data (encoding) Ethan Furman <ethan@stoneleaf.us> - 2012-03-28 11:49 -0700
          RE: "convert" string to bytes without changing data (encoding) "Prasad, Ramit" <ramit.prasad@jpmorgan.com> - 2012-03-28 18:20 +0000
          Re: "convert" string to bytes without changing data (encoding) Ian Kelly <ian.g.kelly@gmail.com> - 2012-03-28 12:20 -0600
          Re: "convert" string to bytes without changing data (encoding) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-03-28 18:26 +0000
            Re: "convert" string to bytes without changing data (encoding) Grant Edwards <invalid@invalid.invalid> - 2012-03-28 19:40 +0000
          Re: "convert" string to bytes without changing data (encoding) Ethan Furman <ethan@stoneleaf.us> - 2012-03-28 11:17 -0700
          Re: "convert" string to bytes without changing data (encoding) John Nagle <nagle@animats.com> - 2012-03-28 12:30 -0700
          Re: "convert" string to bytes without changing data (encoding) Terry Reedy <tjreedy@udel.edu> - 2012-03-28 17:37 -0400
            Re: "convert" string to bytes without changing data (encoding) Peter Daum <gator@cs.tu-berlin.de> - 2012-03-29 16:57 +0200
            Re: "convert" string to bytes without changing data (encoding) Peter Daum <gator@cs.tu-berlin.de> - 2012-03-29 16:57 +0200
          Re: "convert" string to bytes without changing data (encoding) Serhiy Storchaka <storchaka@gmail.com> - 2012-03-30 22:06 +0300
          Re: "convert" string to bytes without changing data (encoding) Chris Angelico <rosuav@gmail.com> - 2012-03-31 06:10 +1100
      Re: "convert" string to bytes without changing data (encoding) Stefan Behnel <stefan_ml@behnel.de> - 2012-03-28 13:25 +0200
      Re: "convert" string to bytes without changing data (encoding) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-03-28 18:12 +0000
    Re: "convert" string to bytes without changing data (encoding) Ross Ridge <rridge@csclub.uwaterloo.ca> - 2012-03-28 11:36 -0400
      Re: "convert" string to bytes without changing data (encoding) Chris Angelico <rosuav@gmail.com> - 2012-03-29 03:18 +1100
        Re: "convert" string to bytes without changing data (encoding) Grant Edwards <invalid@invalid.invalid> - 2012-03-28 16:33 +0000
        Re: "convert" string to bytes without changing data (encoding) Ross Ridge <rridge@csclub.uwaterloo.ca> - 2012-03-28 14:05 -0400
          Re: "convert" string to bytes without changing data (encoding) Tim Chase <python.list@tim.thechases.com> - 2012-03-28 13:49 -0500
            Re: "convert" string to bytes without changing data (encoding) Ross Ridge <rridge@csclub.uwaterloo.ca> - 2012-03-28 15:10 -0400
          Re: "convert" string to bytes without changing data (encoding) "Albert W. Hopkins" <marduk@letterboxes.org> - 2012-03-28 15:22 -0400
      Re: "convert" string to bytes without changing data (encoding) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-03-28 17:54 +0000
        Re: "convert" string to bytes without changing data (encoding) Ross Ridge <rridge@csclub.uwaterloo.ca> - 2012-03-28 14:22 -0400
          Re: Re: "convert" string to bytes without changing data (encoding) Evan Driscoll <driscoll@cs.wisc.edu> - 2012-03-28 14:20 -0500
            Re: Re: "convert" string to bytes without changing data (encoding) Ross Ridge <rridge@csclub.uwaterloo.ca> - 2012-03-28 15:43 -0400
              Re: "convert" string to bytes without changing data (encoding) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-03-28 21:44 +0100
              Re: "convert" string to bytes without changing data (encoding) Neil Cerutti <neilc@norwich.edu> - 2012-03-28 20:56 +0000
              Re: "convert" string to bytes without changing data (encoding) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-03-29 00:02 +0000
              Re: Re: Re: "convert" string to bytes without changing data (encoding) Evan Driscoll <driscoll@cs.wisc.edu> - 2012-03-28 19:11 -0500
                Re: Re: Re: "convert" string to bytes without changing data (encoding) Ross Ridge <rridge@csclub.uwaterloo.ca> - 2012-03-28 23:04 -0400
                Re: Re: Re: "convert" string to bytes without changing data (encoding) Chris Angelico <rosuav@gmail.com> - 2012-03-29 14:31 +1100
                Re: Re: Re: "convert" string to bytes without changing data (encoding) Ross Ridge <rridge@csclub.uwaterloo.ca> - 2012-03-28 23:58 -0400
                Re: "convert" string to bytes without changing data (encoding) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-03-29 07:01 +0100
                Re: "convert" string to bytes without changing data (encoding) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-03-29 06:51 +0000
                Re: "convert" string to bytes without changing data (encoding) Ross Ridge <rridge@csclub.uwaterloo.ca> - 2012-03-29 11:30 -0400
                Re: "convert" string to bytes without changing data (encoding) Terry Reedy <tjreedy@udel.edu> - 2012-03-29 12:49 -0400
                Re: "convert" string to bytes without changing data (encoding) Ross Ridge <rridge@csclub.uwaterloo.ca> - 2012-03-29 14:00 -0400
                Re: "convert" string to bytes without changing data (encoding) Chris Angelico <rosuav@gmail.com> - 2012-03-30 07:41 +1100
                Re: "convert" string to bytes without changing data (encoding) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-03-30 01:16 +0000
                Re: Re: Re: Re: "convert" string to bytes without changing data (encoding) Evan Driscoll <driscoll@cs.wisc.edu> - 2012-03-29 11:31 -0500
          RE: "convert" string to bytes without changing data (encoding) "Prasad, Ramit" <ramit.prasad@jpmorgan.com> - 2012-03-28 19:02 +0000
            Re: "convert" string to bytes without changing data (encoding) Grant Edwards <invalid@invalid.invalid> - 2012-03-28 19:44 +0000
          Re: "convert" string to bytes without changing data (encoding) MRAB <python@mrabarnett.plus.com> - 2012-03-28 20:50 +0100
          RE: "convert" string to bytes without changing data (encoding) "Prasad, Ramit" <ramit.prasad@jpmorgan.com> - 2012-03-29 17:36 +0000
            Re: "convert" string to bytes without changing data (encoding) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-03-30 01:10 +0000
              Re: "convert" string to bytes without changing data (encoding) Michael Ströder <michael@stroeder.com> - 2012-03-30 09:04 +0200
      Re: "convert" string to bytes without changing data (encoding) Terry Reedy <tjreedy@udel.edu> - 2012-03-28 14:11 -0400
  Re: "convert" string to bytes without changing data (encoding) Stefan Behnel <stefan_ml@behnel.de> - 2012-03-28 11:08 +0200
  Re: "convert" string to bytes without changing data (encoding) Dave Angel <d@davea.name> - 2012-03-28 13:16 -0400

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