Write file(s) with all properties of a MATLAB model

Suppose I have built a machine learning model in MATLAB. It has a list of properties (and underlying property data) that encapsulates the model. For example ...

% Set seed for reproducibility
rng default

% Number of observations and features
N_obs = 20;
N_feat = 5;

% Generate some made-up data
x = randn(N_obs,N_feat);
y = randn(N_obs,1);

% Fit a model, and get the properties
mdl = fitrtree(x,y);
modelProperties = sort(properties(mdl));
% Display a few properties
modelProperties(1:3)

ans = 3×1 cell array
    {'BinEdges'             }
    {'CategoricalPredictors'}
    {'CategoricalSplit'     }

I would like to share the property values (not just the property names) with a non-MATLAB user. I'm looking for a clever way to write the values to a text file.

The main stumbling block is that the properties are of many different data types, so I cannot just loop through them and use a single function (e.g. writecell) to write to file. It seems I will need to hard-code a switch statement or the like, to find the appropriate function to write each data type appropriately.

Am I overlooking a more elegant method?

[Bjorn Gustavsson]

Maybe not "elegant" as such, but I instantly thought of the header of fits-files. They contain meta-data with key-word -> meta-data, where the meta-data can be of "very arbitrary" types. As I recall there are good tools for adding meta-data of different types. If that doesn't solve your problem exactly there has to be some other similar tools already handling this. Surely you shouldn't need to re-invent this functionality in 2022?

[Walter Roberson]

struct() and jsonencode()?

Answer 1

[Abderrahim. B]

Hi!

I prefer to use fprintf with fopen and fclose. Once you learn how to design formatSpecifications you will always use fprintf instead of other data writing functions.

You have a cell,, suggest to convert to table, then you write row by row.

Hope this helps

[the cyclist]

I appreciate the response, but I don't think you quite understood the depth of the issue. Maybe I didn't give enough detail.

Yes, the property names are a cell, and it would be trivial to write that cell to file, using either the generic fprintf function or a more specific one like writecell.

But that is not what I am doing. Rather, I need to write the underlying data values for each property. For example, I want to write the property values for "PredictorNames"

mdl.('PredictorNames')

ans =

  1×5 cell array

    {'x1'}    {'x2'}    {'x3'}    {'x4'}    {'x5'}

which is itself a cell array, but other property values might be a numeric array:

    mdl.('X')

ans =

    0.5377    0.6715   -0.1022   -1.0891    1.4193
    1.8339   -1.2075   -0.2414    0.0326    0.2916
   -2.2588    0.7172    0.3192    0.5525    0.1978
    0.8622    1.6302    0.3129    1.1006    1.5877
...

So, via your method, I am still stuck with writing a separate format specification for each property, which is exactly what I am trying to avoid.

(I truly think there is no way around this, but a guy can hope.)