Re: substitution within a substitution list
- To: mathgroup at smc.vnet.net
- Subject: [mg88569] Re: substitution within a substitution list
- From: "jwmerrill at gmail.com" <jwmerrill at gmail.com>
- Date: Fri, 9 May 2008 03:21:08 -0400 (EDT)
- References: <fvudmu$ebg$1@smc.vnet.net>
On May 8, 4:30 am, Bipin <bipin.... at googlemail.com> 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 actually do this pretty much like any other pattern matching.
Just need some strategic parentheses:
{a -> 1, b -> 2, c -> 2} /. (b -> _) -> (b -> 20)
{a -> 1, b -> 20, c -> 2}
JM