From eb3941a617c42b1421bbb4cb591d1e1d5b8d10e9 Mon Sep 17 00:00:00 2001
From: Saurabh7 <saurabh.mahindre@gmail.com>
Date: Wed, 29 Jun 2016 18:31:55 +0530
Subject: [PATCH] shallow subset

---
 src/shogun/features/DenseFeatures.cpp  | 16 ++++++++++++++++
 src/shogun/features/DenseFeatures.h    |  2 ++
 src/shogun/features/Features.h         |  6 ++++++
 src/shogun/labels/DenseLabels.cpp      |  1 +
 src/shogun/labels/Labels.h             |  6 ++++++
 src/shogun/labels/MulticlassLabels.cpp | 14 ++++++++++++++
 src/shogun/labels/MulticlassLabels.h   |  2 ++
 7 files changed, 47 insertions(+)

diff --git a/src/shogun/features/DenseFeatures.cpp b/src/shogun/features/DenseFeatures.cpp
index b782ec68c13..c4f11d5fa50 100644
--- a/src/shogun/features/DenseFeatures.cpp
+++ b/src/shogun/features/DenseFeatures.cpp
@@ -636,6 +636,22 @@ CFeatures* CDenseFeatures<ST>::copy_dimension_subset(SGVector<index_t> dims)
 	return result;
 }
 
+template<class ST>
+CFeatures* CDenseFeatures<ST>::shallow_subset_copy()
+{
+	SG_SDEBUG("Entering!\n");
+	CFeatures* shallow_copy_features=nullptr;
+	
+	SG_SDEBUG("Using underlying feature matrix with %d dimensions and %d feature vectors!\n", num_features, num_vectors);
+	SGMatrix<ST> shallow_copy_matrix = SGMatrix<ST>(feature_matrix.matrix, num_features, num_vectors, false);
+	shallow_copy_features=new CDenseFeatures<ST>(shallow_copy_matrix);
+	if (m_subset_stack->has_subsets())
+		shallow_copy_features->add_subset(m_subset_stack->get_last_subset()->get_subset_idx());
+	
+	SG_SDEBUG("Leaving!\n");
+	return shallow_copy_features;
+}
+
 template<class ST> ST* CDenseFeatures<ST>::compute_feature_vector(int32_t num, int32_t& len,
 		ST* target)
 {
diff --git a/src/shogun/features/DenseFeatures.h b/src/shogun/features/DenseFeatures.h
index 8580884cea0..463fde27fbe 100644
--- a/src/shogun/features/DenseFeatures.h
+++ b/src/shogun/features/DenseFeatures.h
@@ -515,6 +515,8 @@ template<class ST> class CDenseFeatures: public CDotFeatures
 	 */
 	static CDenseFeatures* obtain_from_generic(CFeatures* const base_features);
 
+	virtual CFeatures* shallow_subset_copy();
+
 	/** @return object name */
 	virtual const char* get_name() const { return "DenseFeatures"; }
 
diff --git a/src/shogun/features/Features.h b/src/shogun/features/Features.h
index 9425080d2b4..3a2d8338838 100644
--- a/src/shogun/features/Features.h
+++ b/src/shogun/features/Features.h
@@ -331,6 +331,12 @@ class CFeatures : public CSGObject
 		 * @return whether this class supports compatible computation
 		 */
 		virtual bool get_feature_class_compatibility (EFeatureClass rhs) const;
+
+		virtual CFeatures* shallow_subset_copy() 
+		{ 
+			SG_SNOTIMPLEMENTED;
+			return NULL;
+		}
 	private:
 		void init();
 
diff --git a/src/shogun/labels/DenseLabels.cpp b/src/shogun/labels/DenseLabels.cpp
index 525f43b3d5b..47ae77ada63 100644
--- a/src/shogun/labels/DenseLabels.cpp
+++ b/src/shogun/labels/DenseLabels.cpp
@@ -203,3 +203,4 @@ int32_t CDenseLabels::get_num_labels() const
 	return m_subset_stack->has_subsets()
 			? m_subset_stack->get_size() : m_labels.vlen;
 }
+
diff --git a/src/shogun/labels/Labels.h b/src/shogun/labels/Labels.h
index b77c030dc54..9c1a1bc94bf 100644
--- a/src/shogun/labels/Labels.h
+++ b/src/shogun/labels/Labels.h
@@ -123,6 +123,12 @@ class CLabels : public CSGObject
 	 */
 	virtual SGVector<float64_t> get_values();
 
+	virtual CLabels* shallow_subset_copy()
+	{
+		SG_SNOTIMPLEMENTED;
+		return NULL;
+	}
+
 private:
 	void init();
 
diff --git a/src/shogun/labels/MulticlassLabels.cpp b/src/shogun/labels/MulticlassLabels.cpp
index 161c5361ebc..870f89c62fc 100644
--- a/src/shogun/labels/MulticlassLabels.cpp
+++ b/src/shogun/labels/MulticlassLabels.cpp
@@ -134,3 +134,17 @@ int32_t CMulticlassLabels::get_num_classes()
 	SGVector<float64_t> unique=get_unique_labels();
 	return unique.vlen;
 }
+
+CLabels* CMulticlassLabels::shallow_subset_copy()
+{
+	CLabels* shallow_copy_labels=nullptr;
+	SGVector<float64_t> shallow_copy_vector = SGVector<float64_t>(m_labels.vector, m_labels.size(), false);
+	shallow_copy_labels=new CMulticlassLabels(m_labels.size());
+
+	((CDenseLabels*) shallow_copy_labels)->set_labels(shallow_copy_vector);
+	if (m_subset_stack->has_subsets())
+		shallow_copy_labels->add_subset(m_subset_stack->get_last_subset()->get_subset_idx());
+	
+	SG_SDEBUG("Leaving!\n");
+	return shallow_copy_labels;	
+}
diff --git a/src/shogun/labels/MulticlassLabels.h b/src/shogun/labels/MulticlassLabels.h
index 6d5d75ce1db..86c7d3668c9 100644
--- a/src/shogun/labels/MulticlassLabels.h
+++ b/src/shogun/labels/MulticlassLabels.h
@@ -123,6 +123,8 @@ class CMulticlassLabels : public CDenseLabels
 
 		/** @return object name */
 		virtual const char* get_name() const { return "MulticlassLabels"; }
+		
+		virtual CLabels* shallow_subset_copy();
 
 	private:
 		/** initialises and register parameters */