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MathGroup Archive 1999

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Re: dictionaries?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg20475] Re: dictionaries?
  • From: "Allan Hayes" <hay at haystack.demon.co.uk>
  • Date: Wed, 27 Oct 1999 02:04:44 -0400
  • References: <7v3bov$5tg@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Joe Strout <joe at strout.net> wrote in message news:7v3bov$5tg at smc.vnet.net...
> In Python, there's an extremely handy datatype called a "dictionary"
> which implements a many-to-1 mapping between keys (which can be any
> hashable type) and values (which can be anything).  E.g.:
>
> > d = {"one":1, "two":2}
> > d["one"]
> 1
> > d["three"]
> (key not found)
>
> I'm looking for something similar in Mathematica -- it's a great way to
> organize lists of parameters, without having to worry about the order
> in which they are listed.
>
> I've searched the online help and flipped through the Mathematica book,
> but I can't find anything like this.  Have I missed something?
>
> Thanks,
> -- Joe
>
> --
> ,------------------------------------------------------------------.
> |    Joseph J. Strout           Biocomputing -- The Salk Institute |
> |    joe at strout.net             http://www.strout.net              |
> `------------------------------------------------------------------'
> Check out the Mac Web Directory!    http://www.strout.net/macweb.cgi
>

Joe,
I'm not sure that I understand what you want, but the use of options (such
as for Plot) in Mathematica avoids needing to enter in a definite order.

For example

g[x_, opts___?OptionQ] := A[x, B] /. {opts};

g[3, A -> a, B -> b]

    a[3, b]

g[3,  B -> b, A -> a]

    a[3, b]


--
Allan
---------------------
Allan Hayes
Mathematica Training and Consulting
Leicester UK
www.haystack.demon.co.uk
hay at haystack.demon.co.uk
Voice: +44 (0)116 271 4198
Fax: +44 (0)870 164 0565




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