diff --git a/include/Data/SqpIterator.h b/include/Data/SqpIterator.h
index 962bbe3..2532725 100644
--- a/include/Data/SqpIterator.h
+++ b/include/Data/SqpIterator.h
@@ -9,11 +9,11 @@
  * @tparam T the type of object handled in iterator
  * @sa http://www.cplusplus.com/reference/iterator/
  */
-template <typename T>
+template <typename T, bool isConst=false>
 class SCIQLOP_CORE_EXPORT SqpIterator {
 public:
     using iterator_category = std::random_access_iterator_tag;
-    using value_type = const T;
+    using value_type = typename std::conditional<isConst, const T, T>::type;
     using difference_type = std::ptrdiff_t;
     using pointer = value_type *;
     using reference = value_type &;
diff --git a/src/Data/SpectrogramSeries.cpp b/src/Data/SpectrogramSeries.cpp
index 4bfb435..81b8500 100644
--- a/src/Data/SpectrogramSeries.cpp
+++ b/src/Data/SpectrogramSeries.cpp
@@ -1,4 +1,5 @@
 #include <Data/SpectrogramSeries.h>
+#include <Data/DataSeriesUtils.h>
 
 SpectrogramSeries::SpectrogramSeries(std::vector<double> xAxisData, std::vector<double> yAxisData,
                                      std::vector<double> valuesData, const Unit &xAxisUnit,
@@ -22,6 +23,10 @@ SpectrogramSeries::SpectrogramSeries(std::shared_ptr<ArrayData<1> > xAxisData,
                      std::move(yAxis)},
           m_XResolution{resolution}
 {
+    if(std::isnan(m_XResolution))
+    {
+        //m_XResolution = DataSeriesUtils::resolution(xAxisData->begin(), xAxisData->end()).m_Val;
+    }
 }
 
 std::unique_ptr<IDataSeries> SpectrogramSeries::clone() const
diff --git a/src/pybind11_wrappers/CoreWrappers.cpp b/src/pybind11_wrappers/CoreWrappers.cpp
index a37c263..26620ce 100644
--- a/src/pybind11_wrappers/CoreWrappers.cpp
+++ b/src/pybind11_wrappers/CoreWrappers.cpp
@@ -4,6 +4,8 @@
 #include <pybind11/numpy.h>
 #include <pybind11/chrono.h>
 #include <pybind11/functional.h>
+#include <pybind11/stl.h>
+
 
 #include <string>
 #include <sstream>
@@ -69,6 +71,7 @@ PYBIND11_MODULE(pysciqlopcore,m){
 
     py::class_<DataSeriesIteratorValue>(m,"DataSeriesIteratorValue")
             .def_property_readonly("x", &DataSeriesIteratorValue::x)
+            .def_property_readonly("y", &DataSeriesIteratorValue::y)
             .def("value", py::overload_cast<>(&DataSeriesIteratorValue::value, py::const_))
             .def("value", py::overload_cast<int>(&DataSeriesIteratorValue::value, py::const_))
             .def("values", &DataSeriesIteratorValue::values);