[WIP] Trying to fix mini-batch variants of GD.

src/DataSet/DataSet.h

@@ -77,6 +77,7 @@ namespace lib4neuro {
 
         arma::Mat<double>* outputs_matrix;
 
+        unsigned int last_batch_vector_ind = 0;
 
     public:
 
@@ -315,9 +316,23 @@ namespace lib4neuro {
          * @param max
          * @return
          */
+        [[deprecated("get_next_random_data_batch() should be used instead")]]
         LIB4NEURO_API std::vector<std::pair<std::vector<double>, std::vector<double>>>
         get_random_data_batch(size_t max);
 
+        /**
+         * Function, that returns being&end iterators of the next random disjunct batch of DataSet.
+         * Randomness is given by copying the current DataSet, shuffling it once by Fisher-Yates algorithm and then
+         * selecting first 'max' elements, which weren't selected before.
+         *
+         * If the shuffled vector is depleted, the process repeats with copying the DataSet again and another random
+         * shuffle...
+         *
+         * @param max
+         * @return
+         */
+        LIB4NEURO_API std::vector<std::pair<std::vector<double>, std::vector<double>>> get_next_data_batch(size_t max);
+
 		/**
 		 * Adds a new output column filled with zeros 
 		 * @param n_columns Number of columns to be inserted