Re: data structures
- To: mathgroup at smc.vnet.net
- Subject: [mg22697] Re: data structures
- From: "Allan Hayes" <hay at haystack.demon.co.uk>
- Date: Wed, 22 Mar 2000 00:28:04 -0500 (EST)
- References: <8av7mf$jab@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Maarten,
I give below a quick and simple response, taking up the pattern of your
example. This clearly has lots of problems. But
Roman Maeder, The Mathematica Progammer,
has a chapter on Databases.
person[i_, x : street | city] := person[i, address, x];
person[i_, address] := person[i, #] & /@ {street, city};
person[1, name] = "Jeff";
person[1, length] = 180;
person[1, address, street] = "Church Road";
person[1, address, city] = "London";
person[1, favouriteColours[1]] = "green";
person[1.favouriteColours[2]] = "purple";
person[2, name] = "Jane";
person[2, length] = 175;
person[2, address, street] = "Farm Road";
person[2, address, city] = "York";
person[2, favouriteColours[1]] = "pink";
person[2, favouriteColours[2]] = "green";
Do[Print[person[i, street]], {i, 2}]
Print[person[1, address] // TableForm]
Sum[person[i, length], {i, 2}]
--
Allan
---------------------
Allan Hayes
Mathematica Training and Consulting
Leicester UK
www.haystack.demon.co.uk
hay at haystack.demon.co.uk
Voice: +44 (0)116 271 4198
Fax: +44 (0)870 164 0565
<Maarten.vanderBurgt at icos.be> wrote in message
news:8av7mf$jab at smc.vnet.net...
> Hi,
>
> Is there an elegant way of setting up data structures like you can do in
> languages like C?
> Something like the following example (what follows is a mixture between
> mathematica code and C) explains what I am looking for:
>
> Table[ person[i], {i,1,10}]
>
> person[1].name = "Jeff"
> person[1].length = 180
> person[1].address.street = "Church Road"
> person[1].address.city = "London"
> person[1].favourite_colours[1]= "green"
> person[1].favourite_colours[2]= "pruple"
>
> person[2].name = "Jane"
> person[2].length = 175
> person[2].address.street = "Farm Road"
> ...
>
> person[10]....
>
> Then you can do things like:
>
> Do[Print[ person[i].street ], {i,1,10}],
>
> or
>
> totallength = Apply[Plus, Table[ person[i].length, {i,1,10}]].
>
>
>
> I know you could do something similar with nested lists.
> But I do not want to remember that index 1 corresponds to 'name', index 2
> corresponds to 'length' and that index 3,2 is 'city' and so on.
>
>
> Any suggestions are welcome.
> Thanks
>
> Maarten van der Burgt
> Leuven, Belgium
>
>
>
>
>
>
>