Re: harder parts of list

• To: mathgroup at smc.vnet.net
• Subject: [mg15600] Re: [mg15570] harder parts of list
• From: "Clemens Frey" <Clemens.Frey at uni-bayreuth.de>
• Date: Thu, 28 Jan 1999 04:23:29 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

```Dear Arnold,
this is not so difficult as it seems at first. Just use one of the
following Maps of pure functions to solve the problem restated below:

Function[
sublst,
Select[Rest[sublst],#<First[sublst]&]
] /@ lst

Function[
sublst,
Cases[Rest[sublst],x_/;x<First[sublst]] ] /@ lst

Both of them gives the result you want. If you like it more explicit,
you could write alternatively:

sel[lst_] := Select[Rest[lst],#<First[lst]&]; sel /@ lst

which is the same as above without the use of the outer pure function.
Hope this helped
Clemens

------------------------------------------------------------
Clemens Frey
Doctoral Fellow at the
Department of Mathematics/BITOEK
University of Bayreuth(Germany)

clemens.frey at uni-bayreuth.de
http://www.bitoek.uni-bayreuth.de/~Clemens.Frey
------------------------------------------------------------

>This seems to be a harder list parts problem. Given a list like
>
>lst={{4,2,3,1},{3,1,5},{2,4,3}}
>
>I wish to select the elements in each sublist that are smaller than the
>first
>  entry in that sublist.
> So for the above lst the output should be {{2,3,1},{1},{}}. How can I
>do this  with Select or Cases?
>
>
>Using pattern matching this works
>
>rule1={a_,b___,c_,d___}:>{a,b,d} /;c>a
>
>
>(# //. rule1)& /@ lst
>
>{{4,2,3,1},{3,1},{2}}
>
>Rest /@ %
>
>{{2,3,1},{1},{}}
>
>Thanks
>Arnold Knopfmacher
>Wiws University
>South Africa
>
>

```

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