Re: How to dynamically build a list of rules
- To: mathgroup at smc.vnet.net
- Subject: [mg109156] Re: How to dynamically build a list of rules
- From: telefunkenvf14 <rgorka at gmail.com>
- Date: Wed, 14 Apr 2010 05:16:03 -0400 (EDT)
- References: <hq3a2h$nbr$1@smc.vnet.net>
On Apr 13, 9:42 pm, janitor048 <janitor... at googlemail.com> wrote:
> Hi there!
>
> I need a somewhat larger list of substitution rules along the line of
>
> subs = { name1 -> SomeFunction[name1], name2 ->
> SomeFunction[name2], ... , nameN -> SomeFunction[nameN]}
>
> Obviously typing that by hand can become a little annoying. So I would
> like to have that list created dynamically, via Table[ ... ] or
> something the like.
> The problem is, I can't figure out the correct syntax for this task.
> "name1" etc. are just, well, names (variable names to be specific).
> Unfortunately I haven't been able to find a solution on the web so
> far. Any suggestions?
>
> Cheers,
> Oliver
I think Thread[] is what you want. David Park's website includes a
notebook with a notebook on evaluation control, and examples like:
2 a + 5 d + 3 x
%/. Thread[{a, d, x} -> {8, 3, 4}]
or
2 a + 5 d + 3 x
% /. Thread[Rule[{a, d, x}, {8, 3, 4}]]
-RG