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Re: Is there any efficient easy way to compare two lists with the same length with Mathematica?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg124387] Re: Is there any efficient easy way to compare two lists with the same length with Mathematica?
  • From: James Stein <mathgroup at stein.org>
  • Date: Wed, 18 Jan 2012 05:58:07 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com

I learned something from the answer(s) on this thread, leading to a
question of my own: Why do 'Equal' and 'SameQ' respond differently
from  'Greater' and 'Less' ? e.g.:

a = {1, 2, 3};
b = {3, 2, 1};
Thread[a < b]
Thread[a == b]
Thread[a === b]
Thread[b < a]

On Tue, Jan 17, 2012 at 4:01 AM, Bill Rowe <readnews at sbcglobal.net> wrote:

> On 1/17/12 at 3:34 AM, aoirex at gmail.com (Rex) wrote:
>
> >Given two lists `A={a1,a2,a3,...an}` and `B={b1,b2,b3,...bn}`, I
> >would say `A>=B` if and only if all `ai>=bi`.
>
> >There is a built-in logical comparison of two lists, `A==B`, but no
> >`A>B`. Do we need to compare each element like this
>
> >And@@Table[A[[i]]>=B[[i]],{i,n}]
>
> I think you do need to do an element by element comparison. But
> you don't need to specifically select each element using Part as
> you are doing. That is:
>
> In[13]:= {a, b} = RandomInteger[100, {2, 5}];
> And @@ Thread[a > b]
>
> Out[14]= False
>
> In[15]:= c = RandomInteger[{150, 200}, 5];
> And @@ Thread[c > a]
>
> Out[16]= True
>
>
>


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