Re: dictionaries?
- To: mathgroup at smc.vnet.net
- Subject: [mg20608] Re: dictionaries?
- From: "John M. Jowett" <John.Jowett at cern.ch>
- Date: Thu, 4 Nov 1999 02:13:27 -0500
- Organization: CERN
- References: <7v3bov$5tg@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Joe Strout wrote:
>
> 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
Depending on exactly what you want to do, Mathematica's rules may be fit
the bill, e.g., define a named set of rules
d = {one->1,two->2}
then you can have things like
In[6]:=
x[one] /. d
Out[6]=
x[1]
In[8]:=
two + three /. d
Out[8]=
2 + three
Rules are often a handy one to store a set of substitutions.
John Jowett
--
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My home page: http://wwwslap.cern.ch/~jowett/
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