diff --git a/DebugHelpers/datetimerange.py b/DebugHelpers/datetimerange.py
index 24fed30..b6a781d 100644
--- a/DebugHelpers/datetimerange.py
+++ b/DebugHelpers/datetimerange.py
@@ -30,3 +30,4 @@ def qdump__DateTimeRange(d , value):
                 d.putValue(tstop)
             with SubItem(d, "delta"):
                 d.putValue(delta)
+
diff --git a/external/TimeSeries b/external/TimeSeries
index f5f4deb..22e3e45 160000
--- a/external/TimeSeries
+++ b/external/TimeSeries
@@ -1 +1 @@
-Subproject commit f5f4debc597b41ab1849dfc02b6e092bf58c32d2
+Subproject commit 22e3e4553178230053aac40131b4fdb36c163075
diff --git a/include/Common/cpp_utils.h b/include/Common/cpp_utils.h
index 76739ac..201d837 100644
--- a/include/Common/cpp_utils.h
+++ b/include/Common/cpp_utils.h
@@ -1,29 +1,37 @@
 #ifndef CPP_UTILS_H
 #define CPP_UTILS_H
 
+#include <functional>
+#include <tuple>
 #include <type_traits>
 
-template< class... >
-using void_t = void;
+template<class...> using void_t = void;
 
-#define HAS_METHOD(method)\
-template <class T, class=void>\
-struct _has_##method : std::false_type{};\
-\
-template <class T>\
-struct _has_##method<T, void_t<std::is_member_function_pointer<decltype(&T::method)>>>\
-       : std::true_type{};\
-\
-template< class T>\
-static inline constexpr bool has_##method = _has_##method<T>::value;
+#define HAS_METHOD(method)                                                     \
+  template<class T, class = void> struct _has_##method : std::false_type       \
+  {};                                                                          \
+                                                                               \
+  template<class T>                                                            \
+  struct _has_##method<                                                        \
+      T, void_t<std::is_member_function_pointer<decltype(&T::method)>>>        \
+      : std::true_type                                                         \
+  {};                                                                          \
+                                                                               \
+  template<class T>                                                            \
+  static inline constexpr bool has_##method = _has_##method<T>::value;
 
-//taken from here https://www.fluentcpp.com/2017/10/27/function-aliases-cpp/
-#define ALIAS_TEMPLATE_FUNCTION(highLevelF, lowLevelF)                                             \
-    template <typename... Args>                                                                    \
-    inline auto highLevelF(Args &&... args)->decltype(lowLevelF(std::forward<Args>(args)...))      \
-    {                                                                                              \
-        return lowLevelF(std::forward<Args>(args)...);                                             \
-    }
+// taken from here https://www.fluentcpp.com/2017/10/27/function-aliases-cpp/
+#define ALIAS_TEMPLATE_FUNCTION(highLevelF, lowLevelF)                         \
+  template<typename... Args>                                                   \
+  inline auto highLevelF(Args&&... args)                                       \
+      ->decltype(lowLevelF(std::forward<Args>(args)...))                       \
+  {                                                                            \
+    return lowLevelF(std::forward<Args>(args)...);                             \
+  }
 
+template<typename T> constexpr T diff(const std::pair<T, T>& p)
+{
+  return p.second - p.first;
+}
 
 #endif // CPP_UTILS_H
diff --git a/include/Data/SpectrogramTimeSerie.h b/include/Data/SpectrogramTimeSerie.h
index 4dd3c2a..b453f06 100644
--- a/include/Data/SpectrogramTimeSerie.h
+++ b/include/Data/SpectrogramTimeSerie.h
@@ -18,10 +18,10 @@ public:
           .begin());
 
   SpectrogramTimeSerie() {}
-  SpectrogramTimeSerie(SpectrogramTimeSerie::axis_t& t,
-                       SpectrogramTimeSerie::axis_t& y,
+  SpectrogramTimeSerie(SpectrogramTimeSerie::axis_t&& t,
+                       SpectrogramTimeSerie::axis_t&& y,
                        SpectrogramTimeSerie::container_type<
-                           SpectrogramTimeSerie::raw_value_type>& values,
+                           SpectrogramTimeSerie::raw_value_type>&& values,
                        std::vector<std::size_t>& shape)
       : TimeSeries::TimeSerie<double, SpectrogramTimeSerie, 2>(t, values, shape)
   {
diff --git a/include/Data/TimeSeriesUtils.h b/include/Data/TimeSeriesUtils.h
index 0d32b8e..daeda64 100644
--- a/include/Data/TimeSeriesUtils.h
+++ b/include/Data/TimeSeriesUtils.h
@@ -6,6 +6,7 @@
 #include "VectorTimeSerie.h"
 
 #include <TimeSeries.h>
+#include <cmath>
 #include <memory>
 
 namespace TimeSeriesUtils
@@ -36,6 +37,47 @@ namespace TimeSeriesUtils
     }
     return nullptr;
   }
+
+  struct axis_properties
+  {
+    double range;
+    double max_resolution;
+    bool is_log;
+  };
+
+  constexpr auto IsLog    = true;
+  constexpr auto IsLinear = false;
+
+  constexpr auto CheckMedian     = true;
+  constexpr auto DontCheckMedian = false;
+
+  template<bool is_log, bool check_median>
+  axis_properties axis_analysis(
+      typename std::conditional<is_log, std::vector<double>&,
+                                const std::vector<double>&>::type axis)
+  {
+    std::vector<double> axis_diff(axis.size());
+    if constexpr(is_log)
+    {
+      std::transform(std::cbegin(axis), std::cend(axis), std::begin(axis),
+                     [](const auto v) { return std::log10(v); });
+    }
+    auto range = *(std::cend(axis) - 1) - *(std::begin(axis));
+    std::adjacent_difference(std::cbegin(axis), std::cend(axis),
+                             std::begin(axis_diff));
+    auto min_diff =
+        (*std::min_element(std::cbegin(axis_diff) + 1, std::cend(axis_diff)));
+    if constexpr(check_median)
+    {
+      std::nth_element(std::begin(axis_diff) + 1,
+                       std::begin(axis_diff) + axis_diff.size() / 2,
+                       std::end(axis_diff));
+      auto median_diff = *(std::begin(axis_diff) + axis_diff.size() / 2);
+      if(median_diff > (4 * min_diff)) min_diff = median_diff;
+    }
+    return {range, min_diff, is_log};
+  }
+
 } // namespace TimeSeriesUtils
 
 #endif
diff --git a/src/Variable/Variable2.cpp b/src/Variable/Variable2.cpp
index 8a1a1aa..0d6c40b 100644
--- a/src/Variable/Variable2.cpp
+++ b/src/Variable/Variable2.cpp
@@ -193,6 +193,16 @@ _merge(std::vector<TimeSeries::ITimeSerie*> source, const DateTimeRange& range)
                     std::back_inserter(*std::dynamic_pointer_cast<T>(dest)));
         }
       });
+  if(source.size())
+  {
+    const auto& first = *source.begin();
+    for(std::size_t ax_index = 1; ax_index < first->shape().size(); ax_index++)
+    {
+      const auto& ax = first->axis(ax_index);
+      std::copy(std::cbegin(ax), std::cend(ax),
+                std::back_inserter(dest->axis(ax_index)));
+    }
+  }
   return dest;
 }
 
diff --git a/src/pybind11_wrappers/CoreWrappers.cpp b/src/pybind11_wrappers/CoreWrappers.cpp
index 40e2b53..0161d2c 100644
--- a/src/pybind11_wrappers/CoreWrappers.cpp
+++ b/src/pybind11_wrappers/CoreWrappers.cpp
@@ -232,7 +232,10 @@ PYBIND11_MODULE(pysciqlopcore, m)
       .def(py::init<const std::vector<std::size_t>>())
       .def(py::init([](py::array_t<double> t, py::array_t<double> y,
                        py::array_t<double> values) {
-        assert(t.size() < values.size()); // TODO check geometry
+        auto t_s = t.size();
+        auto v_s = values.size();
+        assert(t.size() < values.size() or
+               t.size() == 0); // TODO check geometry
         assert(y.size() == values.shape(1));
         SpectrogramTimeSerie::axis_t _t(t.size());
         SpectrogramTimeSerie::axis_t _y(y.size());
@@ -243,7 +246,8 @@ PYBIND11_MODULE(pysciqlopcore, m)
         std::vector<std::size_t> shape;
         shape.push_back(values.shape(0));
         shape.push_back(values.shape(1));
-        return SpectrogramTimeSerie(_t, _y, _values, shape);
+        return SpectrogramTimeSerie(std::move(_t), std::move(_y),
+                                    std::move(_values), shape);
       }))
       .def("__getitem__",
            [](SpectrogramTimeSerie& ts,