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Re: substitution within a substitution list

  • To: mathgroup at smc.vnet.net
  • Subject: [mg88580] Re: [mg88551] substitution within a substitution list
  • From: Christopher Carlson <carlson at wolfram.com>
  • Date: Fri, 9 May 2008 03:23:10 -0400 (EDT)
  • References: <200805080813.EAA14310@smc.vnet.net>

On May 8, 2008, at 3:13 AM, Bipin wrote:
> HI,
>
> I'm trying to find a way of changing the substitution values within a
> substitution list.
>
> For example, if I have the following substitution list:-
>
> subs = {a->1, b->2, c->2}
>
> I want to programmatically replace the value associated with 'b' from
> 2 to 20, ie ending up with
>
> subs = {a->1, b->20, c->2}
>
> Does anyone know of a mathematica function for doing this?
>
> Bipin.


You can use

	subs /. HoldPattern[b -> _] :> (b -> 20)

or even something like

	subs /. HoldPattern[b -> x_] :> (b -> 10 x)

Christopher Carlson
User Interface Group
Wolfram Research, Inc.



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