ENH: Added data check before creating a new DataSet - prevents SEGFAULTs...

ENH: Added data check before creating a new DataSet - prevents SEGFAULTs occuring when read() method was not called beforehand.

src/CSVReader/CSVReader.cpp

@@ -80,10 +80,15 @@ namespace lib4neuro {
 
         std::vector<std::pair<std::vector<double>, std::vector<double>>> data_set_contents;
 
-        for(auto line : *this->data) {
+        if(this->data->empty()) {
+            THROW_LOGIC_ERROR("DataSet can not be created as there were no data read beforehand! Did you forget to call "
+                              "the method 'read()'?");
+        }
+
+        for (auto line : *this->data) {
             //TODO check empty values in data
             std::vector<double> input;
-            for(auto ind : *input_col_indices) {
+            for (auto ind : *input_col_indices) {
                 std::string s;
 
                 try {
@@ -102,16 +107,17 @@ namespace lib4neuro {
                     /* Add loaded number to the vector of inputs */
                     input.push_back(tmp);
 
-                } catch(const std::out_of_range& e) {
+                } catch (const std::out_of_range& e) {
                     THROW_OUT_OF_RANGE_ERROR("Non-existing index specified (" + std::to_string(ind) + ")!");
 
                 } catch (const boost::bad_lexical_cast& e) {
-                    THROW_RUNTIME_ERROR("Value \"" + s + "\" is not numerical and so it cannot be used in Data Set!");
+                    THROW_RUNTIME_ERROR(
+                            "Value \"" + s + "\" is not numerical and so it cannot be used in Data Set!");
                 }
             }
 
             std::vector<double> output;
-            for(auto ind : *output_col_indices) {
+            for (auto ind : *output_col_indices) {
                 output.emplace_back(std::stod(line.at(ind)));
             }