Re: python implementation of a new integer encoding algorithm.

References	(3 earlier) <mailman.18823.1424278025.18130.python-list@python.org> <2a717ffb-d61d-4407-9082-1c17cd7ee573@googlegroups.com> <mailman.18839.1424298000.18130.python-list@python.org> <993f64c3-fc85-48a7-9d02-a4f12ecb33c6@googlegroups.com> <54E62A68.4010603@davea.name>
Date	2015-02-20 05:34 +1100
Subject	Re: python implementation of a new integer encoding algorithm.
From	Chris Angelico <rosuav@gmail.com>
Newsgroups	comp.lang.python
Message-ID	<mailman.18895.1424370900.18130.python-list@python.org> (permalink)

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On Fri, Feb 20, 2015 at 5:24 AM, Dave Angel <davea@davea.name> wrote:
> In all my experimenting, I haven't found any values where the 7bit scheme
> does worse.  It seems likely that for extremely large integers, it will, but
> if those are to be the intended distribution, the 7bit scheme could be
> replaced by something else, like just encoding a length at the beginning,
> and using raw bytes after that.

Encoding a length (as varlen) and then using eight bits to the byte
thereafter is worse for small numbers, breaks even around 2**56, and
then is better. So unless your numbers are mainly going to be above
2**56, it's better to just use varlen for the entire number. On the
other hand, if you have to stream this without over-reading (imagine
streaming from a TCP/IP socket; you want to block until you have the
whole number, but not block after that), it may be more efficient to
take the length, and then do a blocking read for the main data,
instead of a large number of single-byte reads. But on the gripping
hand, you can probably just do those one-byte reads and rely on (or
implement) lower-level buffering.

Ask not the python-list for advice, because they will say both "yes"
and "no" and "maybe"... because they will say all three of "yes",
"no", "maybe", and "you don't need to do that"... erm, AMONG our
responses will be such diverse elements as...

ChrisA

Thread

python implementation of a new integer encoding algorithm. janhein.vanderburg@gmail.com - 2015-02-17 03:22 -0800
  Re: python implementation of a new integer encoding algorithm. Chris Angelico <rosuav@gmail.com> - 2015-02-18 00:16 +1100
    Re: python implementation of a new integer encoding algorithm. janhein.vanderburg@gmail.com - 2015-02-18 00:55 -0800
      Re: python implementation of a new integer encoding algorithm. Chris Angelico <rosuav@gmail.com> - 2015-02-18 20:36 +1100
        Re: python implementation of a new integer encoding algorithm. janhein.vanderburg@gmail.com - 2015-02-18 11:29 -0800
      Re: python implementation of a new integer encoding algorithm. Laura Creighton <lac@openend.se> - 2015-02-18 11:32 +0100
        Re: python implementation of a new integer encoding algorithm. janhein.vanderburg@gmail.com - 2015-02-18 11:48 -0800
      People hated it for the same reasons I found them cool (was: python implementation of a new integer encoding algorithm.) Ben Finney <ben+python@benfinney.id.au> - 2015-02-18 21:57 +1100
  Re: python implementation of a new integer encoding algorithm. Dave Angel <davea@davea.name> - 2015-02-17 09:12 -0500
    Re: python implementation of a new integer encoding algorithm. janhein.vanderburg@gmail.com - 2015-02-18 00:59 -0800
      Re: python implementation of a new integer encoding algorithm. Dave Angel <davea@davea.name> - 2015-02-18 11:46 -0500
        Re: python implementation of a new integer encoding algorithm. Grant Edwards <invalid@invalid.invalid> - 2015-02-18 17:30 +0000
          Re: python implementation of a new integer encoding algorithm. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-02-18 18:12 +0000
        Re: python implementation of a new integer encoding algorithm. janhein.vanderburg@gmail.com - 2015-02-18 11:55 -0800
          Re: python implementation of a new integer encoding algorithm. Marko Rauhamaa <marko@pacujo.net> - 2015-02-18 23:54 +0200
            Re: python implementation of a new integer encoding algorithm. Marko Rauhamaa <marko@pacujo.net> - 2015-02-19 00:08 +0200
            Re: python implementation of a new integer encoding algorithm. Grant Edwards <invalid@invalid.invalid> - 2015-02-18 22:58 +0000
          Re: python implementation of a new integer encoding algorithm. Dave Angel <davea@davea.name> - 2015-02-18 17:19 -0500
            Re: python implementation of a new integer encoding algorithm. janhein.vanderburg@gmail.com - 2015-02-19 07:45 -0800
              Re: python implementation of a new integer encoding algorithm. Ian Kelly <ian.g.kelly@gmail.com> - 2015-02-19 11:04 -0700
              Re: python implementation of a new integer encoding algorithm. Ian Kelly <ian.g.kelly@gmail.com> - 2015-02-19 11:16 -0700
              Re: python implementation of a new integer encoding algorithm. Dave Angel <davea@davea.name> - 2015-02-19 13:24 -0500
              Re: python implementation of a new integer encoding algorithm. Chris Angelico <rosuav@gmail.com> - 2015-02-20 05:34 +1100
              Re: python implementation of a new integer encoding algorithm. Ian Kelly <ian.g.kelly@gmail.com> - 2015-02-19 11:32 -0700
              Re: python implementation of a new integer encoding algorithm. Dave Angel <davea@davea.name> - 2015-02-19 13:41 -0500
              Re: python implementation of a new integer encoding algorithm. Dave Angel <davea@davea.name> - 2015-02-19 13:46 -0500
              Re: python implementation of a new integer encoding algorithm. Chris Angelico <rosuav@gmail.com> - 2015-02-20 05:49 +1100
      Re: python implementation of a new integer encoding algorithm. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-02-18 17:00 +0000
  Re: python implementation of a new integer encoding algorithm. Chris Angelico <rosuav@gmail.com> - 2015-02-18 01:34 +1100
    Re: python implementation of a new integer encoding algorithm. janhein.vanderburg@gmail.com - 2015-02-18 01:04 -0800
      Re: python implementation of a new integer encoding algorithm. Dave Angel <davea@davea.name> - 2015-02-18 08:54 -0500
        Re: python implementation of a new integer encoding algorithm. janhein.vanderburg@gmail.com - 2015-02-18 11:52 -0800
      Re: python implementation of a new integer encoding algorithm. Chris Angelico <rosuav@gmail.com> - 2015-02-19 01:16 +1100
  Re: python implementation of a new integer encoding algorithm. Dave Angel <davea@davea.name> - 2015-02-17 09:50 -0500
  Re: python implementation of a new integer encoding algorithm. Chris Angelico <rosuav@gmail.com> - 2015-02-18 01:58 +1100
  Re: python implementation of a new integer encoding algorithm. Dave Angel <davea@davea.name> - 2015-02-17 10:18 -0500
  Re: python implementation of a new integer encoding algorithm. Chris Angelico <rosuav@gmail.com> - 2015-02-18 02:25 +1100
  Re: python implementation of a new integer encoding algorithm. Paul Rubin <no.email@nospam.invalid> - 2015-02-17 08:43 -0800
    Re: python implementation of a new integer encoding algorithm. janhein.vanderburg@gmail.com - 2015-02-18 01:06 -0800
  Re: python implementation of a new integer encoding algorithm. Mario Figueiredo <marfig@gmail.com> - 2015-02-19 08:44 +0100
    Re: python implementation of a new integer encoding algorithm. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-02-19 08:06 +0000
      Re: python implementation of a new integer encoding algorithm. Marko Rauhamaa <marko@pacujo.net> - 2015-02-19 10:36 +0200
        Re: python implementation of a new integer encoding algorithm. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-02-19 09:33 +0000
        Re: python implementation of a new integer encoding algorithm. Terry Reedy <tjreedy@udel.edu> - 2015-02-19 14:50 -0500
          Re: python implementation of a new integer encoding algorithm. Marko Rauhamaa <marko@pacujo.net> - 2015-02-19 21:55 +0200
    Re: python implementation of a new integer encoding algorithm. Chris Angelico <rosuav@gmail.com> - 2015-02-19 19:36 +1100
    Re: python implementation of a new integer encoding algorithm. Mario Figueiredo <marfig@gmail.com> - 2015-02-19 10:42 +0100
    Re: python implementation of a new integer encoding algorithm. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-02-19 10:28 +0000
    Re: python implementation of a new integer encoding algorithm. Mario Figueiredo <marfig@gmail.com> - 2015-02-19 14:27 +0100
  Re: python implementation of a new integer encoding algorithm. Jonas Wielicki <jonas@wielicki.name> - 2015-02-19 09:38 +0100
    Re: python implementation of a new integer encoding algorithm. janhein.vanderburg@gmail.com - 2015-02-19 07:58 -0800
  Re: python implementation of a new integer encoding algorithm. Denis McMahon <denismfmcmahon@gmail.com> - 2015-02-20 02:46 +0000
    Re: python implementation of a new integer encoding algorithm. wxjmfauth@gmail.com - 2015-02-20 00:58 -0800

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