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Re: How to do a negative pattern?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg90575] Re: How to do a negative pattern?
  • From: dh <dh at metrohm.ch>
  • Date: Mon, 14 Jul 2008 05:21:23 -0400 (EDT)
  • References: <g5dm6i$ht4$1@smc.vnet.net>




Hi Steve,

pattern negation is done by: Except.

Daniel



Steven Siew wrote:

> I have used the function DeleteCases which has the format

> 

> DeleteCases[expr,pattern]

> 

> However what I wanted is a negative pattern like

> 

> DeleteCases[expr,negpattern]

> 

> But I have no idea how to craft a negative pattern. Alternatively I

> suppose I could do with a DeleteCasesNot function. Something like

> this:

> 

> $ cat file012.out

> Mathematica 5.2 for Students: Microsoft Windows Version

> Copyright 1988-2005 Wolfram Research, Inc.

> 

> In[1]:=

> Out[1]= {stdout}

> 

> In[2]:= (* Write your mathematica code below *)

> 

> In[3]:= mylist={ {1,1},{1,2},{1,3},{2,1},{2,2},{2,3} }

> 

> Out[3]= {{1, 1}, {1, 2}, {1, 3}, {2, 1}, {2, 2}, {2, 3}}

> 

> In[4]:= myselectionA = DeleteCases[mylist,{_,1}]

> 

> Out[4]= {{1, 2}, {1, 3}, {2, 2}, {2, 3}}

> 

> In[5]:= myselectionB = DeleteCasesNot[mylist,{_,3}]

> 

> Out[5]= {{1, 3}, {2, 3}}

> 

> In[6]:= (* End of mathematica code *)

> 

> In[7]:= Quit[];

> 

> 

> Does anyone has any idea how I could code up a DeleteCasesNot

> function?

> 





-- 



Daniel Huber

Metrohm Ltd.

Oberdorfstr. 68

CH-9100 Herisau

Tel. +41 71 353 8585, Fax +41 71 353 8907

E-Mail:<mailto:dh at metrohm.com>

Internet:<http://www.metrohm.com>




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