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MathGroup Archive 2005

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Re: comparing two lists

  • To: mathgroup at smc.vnet.net
  • Subject: [mg54323] Re: [mg54284] comparing two lists
  • From: János <janos.lobb at yale.edu>
  • Date: Thu, 17 Feb 2005 10:30:43 -0500 (EST)
  • References: <200502161936.OAA19139@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Will this work for you ?

In[41]:=
Table[Flatten[
    (Position[m[[i]],
       #1] & ) /@ Select[
      m[[i]], #1 > v[[i]] & ],
    2], {i, 1, Length[v]}]
Out[41]=
{{2}, {1, 2, 3}}

János
On Feb 16, 2005, at 2:36 PM, Curt Fischer wrote:

> Dear Group:
> I want to write a function that accepts a n-vector and an n x m matrix.
> It should return a list of positions in the matrix where mat[[i,j]] >
> vec[[i]].  For example,
> In[287]:=
> vec=Table[Random[],{2}]
> Out[287]=
> {0.482259,0.314393}
> In[288]:=
> mat=Table[Table[Random[],{4}],{2}]
> Out[288]=
> {{0.183706,0.758693,0.462242,0.170041}, 
> {0.457054,0.349658,0.805455,0.127763}}
> I would like myFunc[] to return {{2},{1,2,3}}.
> How could I write this as a pure function?  Ideally I would like to be
> able to Map or Apply my function to the list {mat, vec} and get my  
> result.
> Something like
> Position[#1,_?(#>#2&)]&@@{mat,vec}
> is doomed to fail because the PatternTest required in Position[] messes
> up the slotting of the other arguments.
> Ideas?  How do you nest pure functions?
> -- 
> Curt Fischer

----------------------------------------------
Trying to argue with a politician is like lifting up the head of a  
corpse.
(S. Lem: His Master Voice)


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