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ReplacePart in an If[] construct?

• To: mathgroup at smc.vnet.net
• Subject: [mg67816] ReplacePart in an If[] construct?
• From: gardyloo <gardyloo at mail.wsu.edu>
• Date: Sat, 8 Jul 2006 04:57:06 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

Hi, all,

   It's probably that I'm too tired, but I have a question about using
ReplacePart in an If[] construct. I've made up a (very) minimal example:

In[1]:=
testList = {{3, an, example, list},
   {4, another, example, list}}

Out[1]=
{{3, an, example, list}, {4, another, example, list}}

In[2]:=
(If[  (ListQ[#1] && First[#1] == 4),
    ReplacePart[#1, replaced!, 3];
    ReplacePart[#1, replaced!, 2],
   #1      (*otherwise*)
] & ) /@ testList

Out[2]=
{{3, an, example, list}, {4, replaced!, example, list}}


        Can someone tell me why BOTH the second and third positions in
the second element in testList aren't turned to "replaced!" ?  I have
plenty of other ways of doing this, but this seemed the most
straightforward, and I can't wrap my head around it, for some reason.

          

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Curtis Osterhoudt          
gardyloo at mail.remove_this.wsu.and_this.edu
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• Follow-Ups:
  • Re: ReplacePart in an If[] construct?
    • From: Andrzej Kozlowski <akoz@mimuw.edu.pl>
  • Re: ReplacePart in an If[] construct?
    • From: Andrzej Kozlowski <akoz@mimuw.edu.pl>