[scikit-learn] OMP ended prematurely due to linear dependence in the dictionary

[Benjamin Merkt]

Hi everyone,

I'm using OrthogonalMatchingPursuit to get a sparse coding of a signal 
using a dictionary learned by a KSVD algorithm (pyksvd). However, during 
the fit I get the following RuntimeWarning:

/usr/local/lib/python2.7/dist-packages/sklearn/linear_model/omp.py:391: 
RuntimeWarning:  Orthogonal matching pursuit ended prematurely due to 
linear dependence in the dictionary. The requested precision might not 
have been met.

   copy_X=copy_X, return_path=return_path)

In those cases the results are indeed not satisfactory. I don't get the 
point of this warning as it is common in sparse coding to have an 
overcomplete dictionary an thus also linear dependency within it. That 
should not be an issue for OMP. In fact, the warning is also raised if 
the dictionary is a square matrix.

Might this Warning also point to other issues in the application?


Thanks, Ben