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MathGroup Archive 2005

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Re: comparing two lists

  • To: mathgroup at smc.vnet.net
  • Subject: [mg54325] Re: [mg54284] comparing two lists
  • From: DrBob <drbob at bigfoot.com>
  • Date: Thu, 17 Feb 2005 10:30:44 -0500 (EST)
  • References: <200502161936.OAA19139@smc.vnet.net>
  • Reply-to: drbob at bigfoot.com
  • Sender: owner-wri-mathgroup at wolfram.com

How's this?

vec = {0.482259, 0.314393};
mat = {{0.183706, 0.758693,
  0.462242, 0.170041}, {0.457054, 0.349658, 0.805455, 0.127763}};
g = Flatten /@ Function[{x, y}, Position[x, _?(# > y &)]] @@@ Transpose@# &;
g@{mat, vec}

{{2}, {1, 2, 3}}

Bobby

On Wed, 16 Feb 2005 14:36:02 -0500 (EST), Curt Fischer <tentrillion at gmail.NOSPAM.com> 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?
>



-- 
DrBob at bigfoot.com
www.eclecticdreams.net


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