'Convert coefficient matrix to dense array format.
Converts the ``coef_`` member (back) to a numpy.ndarray. This is the
default format of ``coef_`` and is required for fitting, so calling
this method is only required on models that have previously been
sparsified; otherwise, it is a no-op.
Returns
self : estimator'

def densify(self):

    msg = 'Estimator,    %(name)s,    must    be    fitted    before    densifying.'
    check_is_fitted(self, 'coef_', msg=msg)
    if sp.issparse(self.coef_):
        self.coef_ = self.coef_.toarray()
    return self
