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Re: Ordering function weird?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg82671] Re: Ordering function weird?
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Sun, 28 Oct 2007 03:58:30 -0500 (EST)
  • References: <ffv29v$aph$1@smc.vnet.net>

Hi,

(y[[#]] & /@ Ordering[y]) - Sort[y]

may help you.

Otherwise read the Help text for Ordering is say
"Ordering[list] gives the positions in list at which each successive 
element of Sort[list] appears. "

Regards
   Jens


Claus wrote:
> Hi,
> say I've got two sets of number, x and y, which I want to rank. See the 
> example below. I totally expect and want the result of Ordering[x]. But 
> I neiter understand nor expect the result of Ordering[y]. Both Sort[x] 
> and Sort[y] are ok.
> Can anybody explain to me Ordering[y]?
> Thanks,
> Claus
> 
> 
> In[3]:= x = {1, 2, 3, 6, 10, 3, 4}
> y = {1, 2, 7, 8, 9, 1, 2}
> 
> Out[3]= {1, 2, 3, 6, 10, 3, 4}
> 
> Out[4]= {1, 2, 7, 8, 9, 1, 2}
> 
> In[5]:= Sort[x]
> Sort[y]
> 
> Out[5]= {1, 2, 3, 3, 4, 6, 10}
> 
> Out[6]= {1, 1, 2, 2, 7, 8, 9}
> 
> In[7]:= Ordering[x]
> Ordering[y]
> 
> Out[7]= {1, 2, 3, 6, 7, 4, 5}
> 
> Out[8]= {1, 6, 2, 7, 3, 4, 5}
> 


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