made multi-kernel MMD work when the features are updated

src/shogun/statistical_testing/MultiKernelQuadraticTimeMMD.cpp

@@ -106,6 +106,12 @@ void CMultiKernelQuadraticTimeMMD::cleanup()
 {
 	ASSERT(self->m_owner);
 	self->m_kernel_mgr.clear();
+	invalidate_precomputed_distance();
+}
+
+void CMultiKernelQuadraticTimeMMD::invalidate_precomputed_distance()
+{
+	ASSERT(self->m_owner);
 	self->m_pairwise_distance=nullptr;
 	self->m_dtype=D_UNKNOWN;
 }

src/shogun/statistical_testing/MultiKernelQuadraticTimeMMD.h

@@ -54,8 +54,8 @@ class MaxMeasure;
  * shift-invariant kernels. If the kernels are not shift-invariant, then the
  * class CQuadraticTimeMMD should be used multiple times instead of this one.
  *
- * This implementation assumes that features are never updated. If new features
- * are to be used, new instance of this class should be created.
+ * If the features are updated, then (if any) existing precomputed distance
+ * instance has to be invalidated by the owner (CQuadraticTimeMMD instance).
  */
 class CMultiKernelQuadraticTimeMMD : public CSGObject
 {
@@ -80,6 +80,7 @@ class CMultiKernelQuadraticTimeMMD : public CSGObject
 private:
 	struct Self;
 	std::unique_ptr<Self> self;
+	void invalidate_precomputed_distance();
 	SGVector<float64_t> statistic(const internal::KernelManager& kernel_mgr);
 	SGMatrix<float32_t> sample_null(const internal::KernelManager& kernel_mgr);
 	SGVector<float64_t> p_values(const internal::KernelManager& kernel_mgr);

src/shogun/statistical_testing/QuadraticTimeMMD.cpp

@@ -193,6 +193,7 @@ void CQuadraticTimeMMD::set_p(CFeatures* samples_from_p)
 		CTwoDistributionTest::set_p(samples_from_p);
 		get_kernel_mgr().restore_kernel_at(0);
 		self->is_kernel_initialized=false;
+		self->multi_kernel->invalidate_precomputed_distance();
 
 		if (get_kernel() && get_kernel()->get_kernel_type()==K_CUSTOM)
 		{
@@ -214,6 +215,7 @@ void CQuadraticTimeMMD::set_q(CFeatures* samples_from_q)
 		CTwoDistributionTest::set_q(samples_from_q);
 		get_kernel_mgr().restore_kernel_at(0);
 		self->is_kernel_initialized=false;
+		self->multi_kernel->invalidate_precomputed_distance();
 
 		if (get_kernel() && get_kernel()->get_kernel_type()==K_CUSTOM)
 		{