Re: python implementation of a new integer encoding algorithm.

Date	2015-02-19 13:41 -0500
From	Dave Angel <davea@davea.name>
Subject	Re: python implementation of a new integer encoding algorithm.
References	(4 earlier) <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> <CAPTjJmos-_yGWuco-u-vRgimcnQ=CUYVB9b9pW5-AYFtzrCM=Q@mail.gmail.com>
Newsgroups	comp.lang.python
Message-ID	<mailman.18897.1424371314.18130.python-list@python.org> (permalink)

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On 02/19/2015 01:34 PM, Chris Angelico wrote:
> 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,

I only suggested this if it turns out that the distribution is primarily 
extremely large numbers, large enough that 7bit isn't good enough.

As I (and others) have said many times, making it optimal means making 
some assumptions about the distribution of likely values.

> 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
>


-- 
DaveA

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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