Default construction argument for Matrix class

[vetlewi]

If a Matrix object is constructed with a single argument, the argument is currently assumes this argument to be an array containing the matrix. However, I think that the most common way to use the matrix class will not to pass a Numpy array, but to pass the path to the file. It would therefore be more intuitive if one could call the constructor with
mat = ompy.matrix("raw_spectra.m") rather than
mat = ompy.matrix(path="raw_spectra.m")

One way to solve this could be that if there is only one argument, then the constructor checks the type of the argument, and based on if's a string or a Numpy array it proceeds with the appropriate steps.

I suggest that one could do such a check for this with something like:

if Eg is None and Ex is None and std is None and path is None and shape is None and state is None and isinstance(values, str):
      self.load(path)

[ErlendLima]

The downside is that the initialization signature would be quite complicated. A possible solution is to only allow the values/path variable to be set by position while forcing all others to be set by keyword.

To illustrate the problem, it is easy to guess what mat = om.Matrix(values, Eg, Ex) will result in. But what about mat = om.Matrix('raw.m', Eg). Should the Eg array overwrite the loaded array? Should it throw an error? If the former, then mat = om.Matrix('raw.m', values=values) ought to be allowed; load the energy vectors but overwrite the matrix with new values.

Forcing keywords have the other advantage of removing bugs of the type mat = om.Matrix(values, Ex, Eg), since with keywords we get the obviously correct mat = om.Matrix(values, Ex=Ex, Eg=Eg).

[fzeiser]

I agree with Erlend. In the code, we quite often create some (new) matrices using the type mat = om.Matrix(values, Ex, Eg). So I think it might be nice to have following signatures:

• mat = om.Matrix('raw.m') -> load path
• mat = om.Matrix(values, Ex=..., Eg=...) --> load matrix
• mat = om.Matrix('raw.m', Eg) --> give an error
• mat = om.Matrix('raw.m', values=values) --> give an error
• mat = om.Matrix(values) --> is this really relevant / potentially again give an error