fix pickling losses in primal_cd

Author: vene

lightning/impl/primal_cd_fast.pyx

@@ -32,6 +32,12 @@ cdef class LossFunction:
     cdef double beta
     cdef int verbose
 
+    def __getstate__(self):
+        return self.max_steps, self.sigma, self.beta, self.verbose
+
+    def __setstate__(self, state):
+        self.max_steps, self.sigma, self.beta, self.verbose = state
+
     # L2 regularization
 
     cdef void solve_l2(self,

lightning/impl/tests/test_primal_cd.py

@@ -178,7 +178,8 @@ def test_debiasing_l1l2():
                            multiclass=False,
                            debiasing=True,
                            warm_debiasing=warm_debiasing,
-                           max_iter=20, C=0.01, random_state=0)
+                           max_iter=20, C=0.01, random_state=0,
+                           verbose=True)
         clf.fit(mult_csc, mult_target)
         assert_greater(clf.score(mult_csc, mult_target), 0.75)
         assert_equal(clf.n_nonzero(percentage=True), 0.08)