       Creating Objects

• To: mathgroup at smc.vnet.net
• Subject: [mg122287] Creating Objects
• From: Gabriel Landi <gtlandi at gmail.com>
• Date: Sun, 23 Oct 2011 06:25:39 -0400 (EDT)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com

```Dear MathGroup (and perhaps some Wolfram employees),

Does anyone know how to create Objects in Mathematica, such as those produced by LinearModelFit or NDSolve`ProcessEquations?
For instance, let data be a set of statistical data. Then data["Mean"] would give me the mean, data["Values"] would return me the original values, etc.

Here is an example from LinearModelFit:

data = {{0, 1}, {1, 0}, {3, 2}, {5, 4}};
lm = LinearModelFit[data, x, x];
Save["Model.txt",lm];

The saved output is

lm = FittedModel[{"Linear", {0.18644067796610198, 0.6949152542372881},
{{x}, {1, x}}, {0, 0}}, {{1., 1., 1., 1.}}, {{0, 1}, {1, 0}, {3, 2},
{5, 4}}, {{1., 0.}, {1., 1.}, {1., 3.}, {1., 5.}},
Function[Null, Internal`LocalizedBlock[{x}, #1], {HoldAll}]]

Which has, basically, only the data and the fitted parameters. Nonetheless, by doing lm["FitResiduals"] it computes the residuals for me.

In my impression, this is as close as one can get to object-oriented programming in Mathematica, and would be a quite useful feature to use.
I haven't found any documentation on this. Anyone knowns?

Sincerely,

Gabriel Landi

```

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