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Re: Select list elements and exchange them

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  • Subject: [mg109829] Re: Select list elements and exchange them
  • From: "David Park" <djmpark at comcast.net>
  • Date: Wed, 19 May 2010 07:04:09 -0400 (EDT)

Use a Rule with ReplaceAll (/.).

testList /. {_, {3, 4}} -> {100, {3, 4}}
{{11, {2, 3}}, {100, {3, 4}}, {34, {5, 6}}, {51, {7, 8}}}


David Park
djmpark at comcast.net
http://home.comcast.net/~djmpark/  

From: ishii.mitsuo.titanium at nsc.co.jp
[mailto:ishii.mitsuo.titanium at nsc.co.jp] 

Hi

I have a problem.


I have a list.

testList={ {11,{2,3}},{21,{3,4}},{34,{5,6}},{51,{7,8}} }

1) From this list, select any element list such as {x,{3,4}},

 where X is an arbitrary number. 

In general, position of {x,{3,4}} in "testList" is not fixed.

2) Select any element list such as {x,{3,4}} and then  exchange {x,{3,4}} to
{100,{3,4}}.

3)Make a new list finally. 

testListNew={ {11,{2,3}},{100,{3,4}},{34,{5,6}},{51,{7,8}} }

Please teach me how to solve.

Thanks in advance.

Mitsuo Ishii




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