Storing and Loading Definitions / Emulating Associative Arrays

*To*: mathgroup at smc.vnet.net*Subject*: [mg93441] Storing and Loading Definitions / Emulating Associative Arrays*From*: Nikolaus Rath <Nikolaus at rath.org>*Date*: Sat, 8 Nov 2008 03:59:12 -0500 (EST)

Hi, I have a routine that calculates some sequence of numbers. The calculation takes very long, so I would like to store the results in a file. What I would like to do is to pack the data, together with the parameters of its generation, into some sort of associative array. Since I couldn't find such a thing in Mathematica, I came up with the idea of using definitions instead: f[seed_, p_, n_] = (* Complicated computation *) {2,4,4}; data[source] = "simulation"; data[seed] = 42; data[parameters] = {12, 0}; data[values] = f[data[seed], Sequence @@ data[parameters]] Now I would like to (somehow) store this set of definitions: Write[stream, something[data]] and later load it again, possibly with a different name data2 = Read[stream] But what is the function something[] that I have to use for this purpose? If I simply store the expression "data", then it is written literally, without the associated definitions. If I use Definition[data] then the output includes the name "data", so that I cannot easily associate it with "data2" when loading. Is there a simple way to achieve what I want? I guess a way would be to store definitions as an anonymous function: data = Function[{x}, Switch[x, source, "simulation", seed, 42, parameters, {12, 0}, values, f[42, 12, 0]]]; Write[stream, data] but then I still need a way to convert between the anonymous function and the definitions when saving and loading. I do not want to work with the anonymous function all the time, since it seems very difficult to modify any parameters after the initial definition: data = Read[Stream] (* do some stuff *) data[comment] = "Analysis on 11/7 showed that this situation is unli= kely"; (* Write back the data with the comment *) Best, -Nikolaus -- =C2=BBIt is not worth an intelligent man's time to be in the majority. By definition, there are already enough people to do that.=C2=AB -J.H. Hardy PGP fingerprint: 5B93 61F8 4EA2 E279 ABF6 02CF A9AD B7F8 AE4E 425C