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Groups > comp.lang.python > #48235
| Date | 2013-06-15 10:26 +1000 |
|---|---|
| From | Cameron Simpson <cs@zip.com.au> |
| Subject | Re: A few questiosn about encoding |
| References | <kpf7hr$spl$16@news.ntua.gr> |
| Newsgroups | comp.lang.python |
| Message-ID | <mailman.3348.1371256019.3114.python-list@python.org> (permalink) |
On 14Jun2013 16:58, Nikos as SuperHost Support <support@superhost.gr> wrote:
| On 14/6/2013 1:14 μμ, Cameron Simpson wrote:
| >Normally a character in a b'...' item represents the byte value
| >matching the character's Unicode ordinal value.
|
| The only thing that i didn't understood is this line.
| First please tell me what is a byte value
The numeric value stored in a byte. Bytes are just small integers
in the range 0..255; the values available with 8 bits of storage.
| >\x1b is a sequence you find inside strings (and "byte" strings, the
| >b'...' format).
|
| \x1b is a character(ESC) represented in hex format
Yes.
| b'\x1b' is a byte object that represents what?
An array of 1 byte, whose value is 0x1b or 27.
| >>> chr(27).encode('utf-8')
| b'\x1b'
Transcribing the ESC Unicode character to byte storage.
| >>> b'\x1b'.decode('utf-8')
| '\x1b'
Reading a single byte array containing a 27 and decoding it assuming 'utf-8'.
This obtains a single character string containing the ESC character.
| After decoding it gives the char ESC in hex format
| Shouldn't it result in value 27 which is the ordinal of ESC ?
When printing strings, the non-printable characters in the string are
_represented_ in hex format, so \x1b was printed.
| > No, I mean conceptually, there is no difference between a code-point
| > and its ordinal value. They are the same thing.
|
| Why Unicode charset doesn't just contain characters, but instead it
| contains a mapping of (characters <--> ordinals) ?
Look, as far as a computer is concerned a character and an ordinal
are the same thing because you just store character ordinals in
memory when you store a string.
When characters are _displayed_, your Terminal (or web browser or
whatever) takes character ordinals and looks them up in a _font_,
which is a mapping of character ordinals to glyphs (character
images), and renders the character image onto your screen.
| I mean what we do is to encode a character like chr(65).encode('utf-8')
| What's the reason of existence of its corresponding ordinal value
| since it doesn't get involved into the encoding process?
Stop thinking of Unicode code points and ordinal values as separate
things. They are effectively two terms for the same thing. So there
is no "corresponding ordinal value". 65 _is_ the ordinal value.
When you run:
chr(65).encode('utf-8')
you're going:
chr(65) ==> 'A'
Producing a string with just one character in it.
Internally, Python stores an array of character ordinals, thus: [65]
'A'.encode('utf-8')
Walk along all the ordinals in the string and transribe them as bytes.
For 65, the byte encoding in 'utf-8' is a single byte of value 65.
So you get an array of bytes (a "bytes object" in Python), thus: [65]
--
Cameron Simpson <cs@zip.com.au>
The double cam chain setup on the 1980's DOHC CB750 was another one of
Honda's pointless engineering breakthroughs. You know the cycle (if you'll
pardon the pun :-), Wonderful New Feature is introduced with much fanfare,
WNF is fawned over by the press, WNF is copied by the other three Japanese
makers (this step is sometimes optional), and finally, WNF is quietly dropped
by Honda.
- Blaine Gardner, <blgardne@sim.es.com>
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A few questiosn about encoding Νικόλαος Κούρας <nikos.gr33k@gmail.com> - 2013-06-09 03:44 -0700
Re: A few questiosn about encoding Fábio Santos <fabiosantosart@gmail.com> - 2013-06-09 13:18 +0100
Re: A few questiosn about encoding Nobody <nobody@nowhere.com> - 2013-06-09 18:01 +0100
Re: A few questiosn about encoding Chris “Kwpolska” Warrick <kwpolska@gmail.com> - 2013-06-09 19:12 +0200
Re: A few questiosn about encoding Νικόλαος Κούρας <support@superhost.gr> - 2013-06-12 09:09 +0000
Re: A few questiosn about encoding Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-12 09:24 +0000
Re: A few questiosn about encoding Νικόλαος Κούρας <support@superhost.gr> - 2013-06-12 14:23 +0300
Re: A few questiosn about encoding Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2013-06-12 14:52 +0200
Re: A few questiosn about encoding Nobody <nobody@nowhere.com> - 2013-06-12 21:30 +0100
Re: A few questiosn about encoding Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-13 01:40 +0000
Re: A few questiosn about encoding Chris Angelico <rosuav@gmail.com> - 2013-06-13 12:01 +1000
Re: A few questiosn about encoding Nobody <nobody@nowhere.com> - 2013-06-13 11:02 +0100
Re: A few questiosn about encoding Νικόλαος Κούρας <support@superhost.gr> - 2013-06-13 09:21 +0300
Re: A few questiosn about encoding jmfauth <wxjmfauth@gmail.com> - 2013-06-12 23:28 -0700
Re: A few questiosn about encoding Chris Angelico <rosuav@gmail.com> - 2013-06-13 16:48 +1000
Re: A few questiosn about encoding Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-13 00:13 +0000
Re: A few questiosn about encoding Νικόλαος Κούρας <support@superhost.gr> - 2013-06-13 09:09 +0300
Re: A few questiosn about encoding Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-13 07:11 +0000
Re: A few questiosn about encoding Νικόλαος Κούρας <support@superhost.gr> - 2013-06-13 10:42 +0300
Re: A few questiosn about encoding Chris Angelico <rosuav@gmail.com> - 2013-06-13 17:58 +1000
Re: A few questiosn about encoding Νικόλαος Κούρας <support@superhost.gr> - 2013-06-13 11:08 +0300
Re: A few questiosn about encoding Chris Angelico <rosuav@gmail.com> - 2013-06-13 18:20 +1000
Re: A few questiosn about encoding Νικόλαος Κούρας <support@superhost.gr> - 2013-06-13 12:41 +0300
Re: A few questiosn about encoding Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-13 11:49 +0000
Re: A few questiosn about encoding Νικόλαος Κούρας <support@superhost.gr> - 2013-06-13 17:19 +0300
Re: A few questiosn about encoding Cameron Simpson <cs@zip.com.au> - 2013-06-14 11:00 +1000
Re: A few questiosn about encoding Nick the Gr33k <support@superhost.gr> - 2013-06-14 09:59 +0300
Re: A few questiosn about encoding Cameron Simpson <cs@zip.com.au> - 2013-06-14 20:14 +1000
Re: A few questiosn about encoding Nick the Gr33k <support@superhost.gr> - 2013-06-14 16:58 +0300
Re: A few questiosn about encoding Joel Goldstick <joel.goldstick@gmail.com> - 2013-06-14 11:21 -0400
Re: A few questiosn about encoding Nick the Gr33k <support@superhost.gr> - 2013-06-14 18:26 +0300
Re: A few questiosn about encoding Chris Angelico <rosuav@gmail.com> - 2013-06-15 03:03 +1000
Re: A few questiosn about encoding Walter Hurry <walterhurry@lavabit.com> - 2013-06-14 23:32 +0000
Re: A few questiosn about encoding Cameron Simpson <cs@zip.com.au> - 2013-06-15 10:26 +1000
Re: A few questiosn about encoding Denis McMahon <denismfmcmahon@gmail.com> - 2013-06-15 06:34 +0000
Re: A few questiosn about encoding Grant Edwards <invalid@invalid.invalid> - 2013-06-15 14:44 +0000
Re: A few questiosn about encoding Nick the Gr33k <support@superhost.gr> - 2013-06-15 17:49 +0300
Re: A few questiosn about encoding Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-15 15:30 +0000
Re: A few questiosn about encoding Roy Smith <roy@panix.com> - 2013-06-15 10:59 -0400
Re: A few questiosn about encoding Nick the Gr33k <support@superhost.gr> - 2013-06-15 18:14 +0300
Re: A few questiosn about encoding Joel Goldstick <joel.goldstick@gmail.com> - 2013-06-15 11:35 -0400
Re: A few questiosn about encoding Nick the Gr33k <support@superhost.gr> - 2013-06-15 22:26 +0300
Re: A few questiosn about encoding Benjamin Schollnick <benjamin@schollnick.net> - 2013-06-15 16:35 -0400
Re: A few questiosn about encoding Chris “Kwpolska” Warrick <kwpolska@gmail.com> - 2013-06-16 15:45 +0200
Re: A few questiosn about encoding Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-06-14 09:36 +0200
Re: A few questiosn about encoding Nick the Gr33k <support@superhost.gr> - 2013-06-14 10:49 +0300
Re: A few questiosn about encoding Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-06-14 10:22 +0200
Re: A few questiosn about encoding Nick the Gr33k <support@superhost.gr> - 2013-06-14 11:37 +0300
Don't feed the troll... (was: Re: A few questiosn about encoding) Heiko Wundram <modelnine@modelnine.org> - 2013-06-14 11:06 +0200
Re: Don't feed the troll... Nick the Gr33k <support@superhost.gr> - 2013-06-14 12:32 +0300
Re: Don't feed the troll... Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-06-14 13:09 +0200
Re: Don't feed the troll... Nick the Gr33k <support@superhost.gr> - 2013-06-14 15:36 +0300
Re: Don't feed the troll... Joel Goldstick <joel.goldstick@gmail.com> - 2013-06-14 08:44 -0400
Re: Don't feed the troll... Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-06-14 15:25 +0200
Re: Don't feed the troll... Neil Cerutti <neilc@norwich.edu> - 2013-06-14 15:54 +0000
Re: Don't feed the troll... Heiko Wundram <modelnine@modelnine.org> - 2013-06-14 12:15 +0200
Re: Don't feed the troll... Guy Scree <nobody@nowhere.com> - 2013-06-14 18:50 -0400
Re: Don't feed the troll... Denis McMahon <denismfmcmahon@gmail.com> - 2013-06-15 06:31 +0000
Re: Don't feed the troll... Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-06-15 13:04 -0400
Re: Don't feed the troll... Guy Scree <nobody@nowhere.com> - 2013-06-17 16:15 -0400
Re: Don't feed the troll... Chris Angelico <rosuav@gmail.com> - 2013-06-18 07:46 +1000
Re: A few questiosn about encoding Cameron Simpson <cs@zip.com.au> - 2013-06-14 20:19 +1000
Re: A few questiosn about encoding Nick the Gr33k <support@superhost.gr> - 2013-06-14 15:41 +0300
Re: Don't feed the troll... (was: Re: A few questiosn about encoding) Fábio Santos <fabiosantosart@gmail.com> - 2013-06-14 11:20 +0100
Re: Don't feed the troll... (was: Re: A few questiosn about encoding) rusi <rustompmody@gmail.com> - 2013-06-14 04:51 -0700
Re: Don't feed the help-vampire rusi <rustompmody@gmail.com> - 2013-06-14 05:09 -0700
Re: Don't feed the help-vampire Heiko Wundram <modelnine@modelnine.org> - 2013-06-14 14:31 +0200
Re: Don't feed the help-vampire Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-14 10:51 -0600
Re: Don't feed the troll... Nick the Gr33k <support@superhost.gr> - 2013-06-14 15:50 +0300
Re: Don't feed the troll... Zero Piraeus <schesis@gmail.com> - 2013-06-14 09:33 -0400
Re: Don't feed the troll... Nick the Gr33k <support@superhost.gr> - 2013-06-14 15:45 +0300
Re: Don't feed the troll... Heiko Wundram <modelnine@modelnine.org> - 2013-06-14 14:58 +0200
Re: Don't feed the troll... Fábio Santos <fabiosantosart@gmail.com> - 2013-06-14 14:25 +0100
Re: Don't feed the troll... Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-06-14 17:12 +0100
Re: A few questiosn about encoding Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-06-14 12:50 +0200
Re: A few questiosn about encoding Nick the Gr33k <support@superhost.gr> - 2013-06-14 15:59 +0300
Re: A few questiosn about encoding Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-06-14 15:52 +0200
Re: A few questiosn about encoding Cameron Simpson <cs@zip.com.au> - 2013-06-15 10:28 +1000
Re: A few questiosn about encoding Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-06-17 08:49 +0200
Re: Don't feed the troll... Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-06-14 12:57 +0100
Re: Don't feed the troll... (was: Re: A few questiosn about encoding) "D'Arcy J.M. Cain" <darcy@druid.net> - 2013-06-14 13:13 -0400
Re: Don't feed the troll... (was: Re: A few questiosn about encoding) Chris Angelico <rosuav@gmail.com> - 2013-06-15 03:31 +1000
Re: Don't feed the troll... (was: Re: A few questiosn about encoding) Grant Edwards <invalid@invalid.invalid> - 2013-06-14 19:40 +0000
Re: Don't feed the troll "D'Arcy J.M. Cain" <darcy@druid.net> - 2013-06-14 13:56 -0400
Re: Don't feed the troll Tim Chase <python.list@tim.thechases.com> - 2013-06-14 14:00 -0500
Re: Don't feed the troll "D'Arcy J.M. Cain" <darcy@druid.net> - 2013-06-14 15:17 -0400
Re: Don't feed the troll... Ben Finney <ben+python@benfinney.id.au> - 2013-06-15 10:42 +1000
Re: A few questiosn about encoding Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-19 18:46 -0700
Re: A few questiosn about encoding Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-20 06:26 +0000
Re: A few questiosn about encoding MRAB <python@mrabarnett.plus.com> - 2013-06-20 12:43 +0100
Re: A few questiosn about encoding wxjmfauth@gmail.com - 2013-06-20 09:27 -0700
Re: A few questiosn about encoding Chris Angelico <rosuav@gmail.com> - 2013-06-21 02:37 +1000
Re: A few questiosn about encoding MRAB <python@mrabarnett.plus.com> - 2013-06-20 18:17 +0100
Re: A few questiosn about encoding wxjmfauth@gmail.com - 2013-06-23 08:51 -0700
Re: A few questiosn about encoding Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-23 16:30 +0000
Re: A few questiosn about encoding wxjmfauth@gmail.com - 2013-06-25 13:16 -0700
Re: A few questiosn about encoding Chris Angelico <rosuav@gmail.com> - 2013-06-21 03:21 +1000
Re: A few questiosn about encoding Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-06-20 20:43 +0100
Re: A few questiosn about encoding Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-20 06:40 -0700
Re: A few questiosn about encoding Andrew Berg <robotsondrugs@gmail.com> - 2013-06-20 09:04 -0500
Re: A few questiosn about encoding Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-20 08:12 -0700
Re: A few questiosn about encoding Chris Angelico <rosuav@gmail.com> - 2013-06-21 01:26 +1000
Re: A few questiosn about encoding Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-06-20 20:25 +0300
Re: A few questiosn about encoding Chris Angelico <rosuav@gmail.com> - 2013-06-21 01:28 +1000
Re: A few questiosn about encoding Andreas Perstinger <andipersti@gmail.com> - 2013-06-20 19:08 +0200
Re: A few questiosn about encoding Dave Angel <davea@davea.name> - 2013-06-12 08:43 -0400
Re: A few questiosn about encoding Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-06-13 18:46 -0400
Re: A few questiosn about encoding Nick the Gr33k <support@superhost.gr> - 2013-06-14 08:34 +0300
Re: A few questiosn about encoding Zero Piraeus <schesis@gmail.com> - 2013-06-14 02:00 -0400
Re: A few questiosn about encoding Nick the Gr33k <support@superhost.gr> - 2013-06-14 10:28 +0300
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