Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.c > #112833

Re: Warning: assignment from incompatible pointer type

Subject Re: Warning: assignment from incompatible pointer type
Newsgroups comp.lang.c
References (5 earlier) <oidlf0$gne$1@dont-email.me> <oif9q6$s7i$2@dont-email.me> <lIM2B.59754$OJ2.17773@fx37.am4> <MaN2B.26007$3y7.25178@fx35.am4> <oigalp$lg8$1@dont-email.me>
From bartc <bc@freeuk.com>
Message-ID <aQR2B.15044$dH.11239@fx17.am4> (permalink)
Organization virginmedia.com
Date 2017-06-22 17:00 +0100

Show all headers | View raw

On 22/06/2017 12:49, David Brown wrote:
> On 22/06/17 12:42, bartc wrote:

>>>> from collections import Counter
>>> msg = "Now is the time for all good men to come to the aid of their
> country"
>>>> m = msg * 1000000
>>>> print(sorted(Counter(m).items()))
> 
> The Pythonic way is "Find the right tool in the standard library.  Use
> it to do the job - it will be faster than using hand-made methods".
> 
> Testing on a faster computer with msg * 1000000:
> 
> python 2.7 : 9.7 seconds
> python 3.5 : 2.1 seconds
> C : 0.1 seconds.
> 
> pypy : 1.2 seconds
> 
> So we see that the Python version takes just a couple of lines of clear
> code (when written well),

I don't agree it is clear. The original required knowledge of .count(), 
set(), and sorted(); this further needs .items() and Counter().

This is not really programming either. (You might as well write C code 
consisting of sequences of system() calls. That might well invoke a 
Python program.)

And when I tried it, I got about 5 seconds on Py3, and 3.5 seconds on Pypy.

This is the C algorithm expressed in Python:

  def gethist(s):
      counts=[0,]*256
      for c in s:
          counts[ord(c)]+=1
      return counts

and is called like this:

  counts=gethist(msg)
  for i in range(32,256):
      if counts[i]:
          print (chr(i),counts[i])

This version takes 12 seconds in Py3, but now allows pypy to do its 
thing with loops; pypy takes only 0.6 seconds, comparing much more 
closely with C.

-- 
bartc

Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Warning: assignment from incompatible pointer type DFS <nospam@dfs.com> - 2017-06-20 12:48 -0400
  Re: Warning: assignment from incompatible pointer type bartc <bc@freeuk.com> - 2017-06-20 18:08 +0100
    Re: Warning: assignment from incompatible pointer type DFS <nospam@dfs.com> - 2017-06-21 09:32 -0400
      Re: Warning: assignment from incompatible pointer type scott@slp53.sl.home (Scott Lurndal) - 2017-06-21 13:48 +0000
  Re: Warning: assignment from incompatible pointer type Richard Heathfield <rjh@cpax.org.uk> - 2017-06-20 18:15 +0100
    Re: Warning: assignment from incompatible pointer type DFS <nospam@dfs.com> - 2017-06-20 18:00 -0400
      Re: Warning: assignment from incompatible pointer type "James R. Kuyper" <jameskuyper@verizon.net> - 2017-06-20 18:47 -0400
        Re: Warning: assignment from incompatible pointer type bartc <bc@freeuk.com> - 2017-06-21 00:10 +0100
        Re: Warning: assignment from incompatible pointer type DFS <nospam@dfs.com> - 2017-06-20 19:56 -0400
  Re: Warning: assignment from incompatible pointer type "James R. Kuyper" <jameskuyper@verizon.net> - 2017-06-20 13:23 -0400
    Re: Warning: assignment from incompatible pointer type DFS <nospam@dfs.com> - 2017-06-20 18:59 -0400
  Re: Warning: assignment from incompatible pointer type Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-20 19:23 +0100
    Re: Warning: assignment from incompatible pointer type DFS <nospam@dfs.com> - 2017-06-20 18:59 -0400
      Re: Warning: assignment from incompatible pointer type Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2017-06-20 19:46 -0400
      Re: Warning: assignment from incompatible pointer type Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-21 02:05 +0100
        Re: Warning: assignment from incompatible pointer type DFS <nospam@dfs.com> - 2017-06-20 21:37 -0400
          Re: Warning: assignment from incompatible pointer type Richard Heathfield <rjh@cpax.org.uk> - 2017-06-21 09:25 +0100
          Re: Warning: assignment from incompatible pointer type David Brown <david.brown@hesbynett.no> - 2017-06-21 13:35 +0200
            Re: Warning: assignment from incompatible pointer type DFS <nospam@dfs.com> - 2017-06-21 22:30 -0400
              Re: Warning: assignment from incompatible pointer type Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-22 11:03 +0100
              Re: Warning: assignment from incompatible pointer type bartc <bc@freeuk.com> - 2017-06-22 11:10 +0100
                Re: Warning: assignment from incompatible pointer type bartc <bc@freeuk.com> - 2017-06-22 11:42 +0100
                Re: Warning: assignment from incompatible pointer type David Brown <david.brown@hesbynett.no> - 2017-06-22 13:49 +0200
                Re: Warning: assignment from incompatible pointer type bartc <bc@freeuk.com> - 2017-06-22 14:40 +0100
                Re: Warning: assignment from incompatible pointer type bartc <bc@freeuk.com> - 2017-06-22 17:00 +0100
                Re: Warning: assignment from incompatible pointer type David Brown <david.brown@hesbynett.no> - 2017-06-22 20:08 +0200
                Re: Warning: assignment from incompatible pointer type DFS <nospam@dfs.com> - 2017-06-22 15:46 -0400
                Re: Warning: assignment from incompatible pointer type Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-22 14:00 +0100
                Re: Warning: assignment from incompatible pointer type bartc <bc@freeuk.com> - 2017-06-22 14:38 +0100
                Re: Warning: assignment from incompatible pointer type Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-22 17:26 +0100
                Re: Warning: assignment from incompatible pointer type Keith Thompson <kst-u@mib.org> - 2017-06-22 10:21 -0700
                Re: Warning: assignment from incompatible pointer type bartc <bc@freeuk.com> - 2017-06-22 18:26 +0100
                Re: Warning: assignment from incompatible pointer type David Brown <david.brown@hesbynett.no> - 2017-06-22 20:41 +0200
                Re: Warning: assignment from incompatible pointer type Richard Heathfield <rjh@cpax.org.uk> - 2017-06-22 19:59 +0100
                Re: Warning: assignment from incompatible pointer type Keith Thompson <kst-u@mib.org> - 2017-06-22 12:28 -0700
          Re: Warning: assignment from incompatible pointer type Jerry Stuckle <jstucklex@attglobal.net> - 2017-06-21 09:49 -0400
            Re: Warning: assignment from incompatible pointer type DFS <nospam@dfs.com> - 2017-06-21 10:36 -0400
              Re: Warning: assignment from incompatible pointer type Jerry Stuckle <jstucklex@attglobal.net> - 2017-06-21 14:15 -0400
          Re: Warning: assignment from incompatible pointer type Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-21 15:10 +0100

csiph-web