diff --git a/src/shogun/statistical_testing/internals/NextSamples.cpp b/src/shogun/statistical_testing/internals/NextSamples.cpp
index 07df99d9b52..2fd9a08d25f 100644
--- a/src/shogun/statistical_testing/internals/NextSamples.cpp
+++ b/src/shogun/statistical_testing/internals/NextSamples.cpp
@@ -16,9 +16,8 @@
  * along with this program.  If not, see <http:/www.gnu.org/licenses/>.
  */
 
-#include <iostream>
-#include <shogun/statistical_testing/internals/NextSamples.h>
 #include <shogun/features/Features.h>
+#include <shogun/statistical_testing/internals/NextSamples.h>
 
 using namespace shogun;
 using namespace internal;
@@ -28,23 +27,32 @@ NextSamples::NextSamples(index_t num_distributions) : m_num_blocks(0)
 	next_samples.resize(num_distributions);
 }
 
+NextSamples& NextSamples::operator=(const NextSamples& other)
+{
+	clear();
+	m_num_blocks=other.m_num_blocks;
+	next_samples=other.next_samples;
+	return *this;
+}
+
 NextSamples::~NextSamples()
 {
+	clear();
 }
 
-std::vector<std::shared_ptr<CFeatures>>& NextSamples::operator[](index_t i)
+std::vector<Block>& NextSamples::operator[](size_t i)
 {
-	REQUIRE(i >= 0 && i < next_samples.size(),
+	REQUIRE(i>=0 && i<next_samples.size(),
 			"index (%d) must be between [0,%d]!\n",
-			i, next_samples.size() - 1);
+			i, next_samples.size()-1);
 	return next_samples[i];
 }
 
-const std::vector<std::shared_ptr<CFeatures>>& NextSamples::operator[](index_t i) const
+const std::vector<Block>& NextSamples::operator[](size_t i) const
 {
-	REQUIRE(i >= 0 && i < next_samples.size(),
+	REQUIRE(i>=0 && i<next_samples.size(),
 			"index (%d) must be between [0,%d]!\n",
-			i, next_samples.size() - 1);
+			i, next_samples.size()-1);
 	return next_samples[i];
 }
 
@@ -55,6 +63,13 @@ const index_t NextSamples::num_blocks() const
 
 const bool NextSamples::empty() const
 {
-	using type = const std::vector<std::shared_ptr<CFeatures>>;
-	return std::any_of(next_samples.cbegin(), next_samples.cend(), [](type& f) { return f.size() == 0; });
+	using type=const std::vector<Block>;
+	return std::any_of(next_samples.cbegin(), next_samples.cend(), [](type& f) { return f.size()==0; });
+}
+
+void NextSamples::clear()
+{
+	using type=std::vector<Block>;
+	std::for_each(next_samples.begin(), next_samples.end(), [](type& f) { f.clear(); });
+	next_samples.clear();
 }
diff --git a/src/shogun/statistical_testing/internals/NextSamples.h b/src/shogun/statistical_testing/internals/NextSamples.h
index bce175b970b..2993edbff4c 100644
--- a/src/shogun/statistical_testing/internals/NextSamples.h
+++ b/src/shogun/statistical_testing/internals/NextSamples.h
@@ -19,9 +19,10 @@
 #ifndef NEXT_SAMPLES_H__
 #define NEXT_SAMPLES_H__
 
-#include <vector>
 #include <memory>
+#include <vector>
 #include <shogun/lib/common.h>
+#include <shogun/statistical_testing/internals/Block.h>
 
 namespace shogun
 {
@@ -59,7 +60,16 @@ class NextSamples
 private:
 	NextSamples(index_t num_distributions);
 public:
+	/**
+	 * Assignment operator. Clears the current blocks.
+	 */
+	NextSamples& operator=(const NextSamples& other);
+
+	/**
+	 * Destructor
+	 */
 	~NextSamples();
+
 	/**
 	 * Contains a number of blocks (of samples) fetched in the current burst from a
 	 * specified distribution.
@@ -67,13 +77,13 @@ class NextSamples
 	 * @param i determines samples from which distribution
 	 * @return a vector of fetched blocks of features from the specified distribution
 	 */
-	std::vector<std::shared_ptr<CFeatures>>& operator[](index_t i);
+	std::vector<Block>& operator[](size_t i);
 
 	/**
 	 * Const version of the above. This is called when a const instance of NextSamples
 	 * is returned.
 	 */
-	const std::vector<std::shared_ptr<CFeatures>>& operator[](index_t i) const;
+	const std::vector<Block>& operator[](size_t i) const;
 
 	/**
 	 * @return number of blocks fetched from each of the distribution. It is assumed
@@ -89,9 +99,14 @@ class NextSamples
 	 * of the distribution
 	 */
 	const bool empty() const;
+
+	/**
+	 * Method that clears the memory occupied by the feature objects inside.
+	 */
+	void clear();
 private:
 	index_t m_num_blocks;
-	std::vector<std::vector<std::shared_ptr<CFeatures>>> next_samples;
+	std::vector<std::vector<Block>> next_samples;
 };
 
 }