diff --git a/main_package/classes/json_importer.py b/main_package/classes/json_importer.py
index 2e7907a..2cb37f3 100644
--- a/main_package/classes/json_importer.py
+++ b/main_package/classes/json_importer.py
@@ -118,7 +118,6 @@ class JsonImporter(AbstractImporter):
         for indx, sample in enumerate(self.df_samples_list):
             self.df_samples_list[indx] = self.compute_row_delta_sigle_samples_frame(sample,
                                                         time_header_label, columns_header, shifted_cols_header)
-            #print(self.df_samples_list[indx])
         self._concatenated_samples = pd.concat(self.df_samples_list)
 
     def build_list_of_samples_array(self, data_frame):
diff --git a/main_package/classes/sample_path.py b/main_package/classes/sample_path.py
index d1bd3da..aeb71f3 100644
--- a/main_package/classes/sample_path.py
+++ b/main_package/classes/sample_path.py
@@ -25,7 +25,9 @@ class SamplePath:
 
     def build_trajectories(self):
         self.importer.import_data()
-        self._trajectories = tr.Trajectory(self.importer.build_list_of_samples_array(self.importer.concatenated_samples))
+        self._trajectories = \
+            tr.Trajectory(self.importer.build_list_of_samples_array(self.importer.concatenated_samples),
+                          len(self.importer.sorter) + 1)
         #self.trajectories.append(trajectory)
         self.importer.clear_data_frames()
 
diff --git a/main_package/classes/structure.py b/main_package/classes/structure.py
index 7f1bea8..d40ea2d 100644
--- a/main_package/classes/structure.py
+++ b/main_package/classes/structure.py
@@ -12,7 +12,6 @@ class Structure:
     def __init__(self, structure, variables):
         self.structure_frame = structure
         self.variables_frame = variables
-        #self._nodes_indexes = self.list_of_nodes_indexes()
         self.name_label = variables.columns.values[0]
         self.value_label = variables.columns.values[1]
 
diff --git a/main_package/classes/trajectory.py b/main_package/classes/trajectory.py
index a41fb6a..ab97686 100644
--- a/main_package/classes/trajectory.py
+++ b/main_package/classes/trajectory.py
@@ -14,15 +14,17 @@ class Trajectory:
 
     """
 
-    def __init__(self, list_of_columns):
-        print(list_of_columns)
+    def __init__(self, list_of_columns, original_cols_number):
+        if type(list_of_columns[0][0]) != np.float64:
+            raise TypeError('The first array in the list has to be Times')
+        #TODO valutare se vale la pena ordinare la lista di numpy array per tipo
+        self.original_cols_number = original_cols_number
         self._actual_trajectory = np.array(list_of_columns[1:], dtype=np.int).T
         self._times = np.array(list_of_columns[0], dtype=np.float)
-        print(self._times)
 
     @property
     def trajectory(self):
-        return self._actual_trajectory[:, :4]
+        return self._actual_trajectory[:, :self.original_cols_number]
 
     @property
     def complete_trajectory(self):
diff --git a/main_package/tests/test_json_importer.py b/main_package/tests/test_json_importer.py
index 95b9f6e..7d66c8a 100644
--- a/main_package/tests/test_json_importer.py
+++ b/main_package/tests/test_json_importer.py
@@ -109,7 +109,11 @@ class TestJsonImporter(unittest.TestCase):
     def test_import_data(self):
         j1 = ji.JsonImporter('../data', 'samples', 'dyn.str', 'variables', 'Time', 'Name')
         j1.import_data()
+        self.assertEqual(list(j1.variables[j1.variables_key]),
+                         list(j1.concatenated_samples.columns.values[1:len(j1.variables[j1.variables_key]) + 1]))
         print(j1.variables)
+        print(j1.structure)
+        print(j1.concatenated_samples)
 
 
 
diff --git a/main_package/tests/test_trajectory.py b/main_package/tests/test_trajectory.py
new file mode 100644
index 0000000..f983e60
--- /dev/null
+++ b/main_package/tests/test_trajectory.py
@@ -0,0 +1,24 @@
+import unittest
+import numpy as np
+
+import trajectory as tr
+
+
+class TestTrajecotry(unittest.TestCase):
+
+    def test_init(self):
+        cols_list = [np.array([1.2,1.3,.14]), np.arange(1,4), np.arange(4,7)]
+        t1 = tr.Trajectory(cols_list, len(cols_list))
+        self.assertTrue(np.array_equal(cols_list[0], t1.times))
+        self.assertTrue(np.array_equal(np.ravel(t1.complete_trajectory[:, : 1]), cols_list[1]))
+        self.assertTrue(np.array_equal(np.ravel(t1.complete_trajectory[:, 1: 2]), cols_list[2]))
+        self.assertEqual(len(cols_list) - 1, t1.complete_trajectory.shape[1])
+
+    def test_init_first_array_not_float_type(self):
+        cols_list = [np.arange(1, 4), np.arange(4, 7), np.array([1.2, 1.3, .14])]
+        self.assertRaises(TypeError, tr.Trajectory, cols_list, len(cols_list))
+
+
+
+if __name__ == '__main__':
+    unittest.main()