HDF5TomoScan: add energy property

tomoscan/esrf/hdf5scan.py

@@ -90,6 +90,8 @@ class HDF5TomoScan(TomoScanBase):
 
     _DISTANCE_PATH = 'instrument/detector/distance'
 
+    _ENERGY_PATH = 'beam/incident_energy'
+
     _SCHEME = 'silx'
 
     _EPSILON_ROT_ANGLE = 0.02
@@ -148,6 +150,7 @@ class HDF5TomoScan(TomoScanBase):
         self._image_keys = None
         self._rotation_angles = None
         self._distance = None
+        self._energy = None
 
     @staticmethod
     def get_master_file(scan_path):
@@ -477,6 +480,15 @@ class HDF5TomoScan(TomoScanBase):
                 self._distance = self._get_value(distance_dataset, default_unit='m')
         return self._distance
 
+    @property
+    def energy(self) -> typing.Union[None, float]:
+        if (self._energy is None and self.master_file and
+                os.path.exists(self.master_file)):
+            with h5py.File(self.master_file, 'r') as h5_file:
+                energy_dataset = h5_file[self._entry][self._ENERGY_PATH]
+                self._energy = self._get_value(energy_dataset, default_unit='keV')
+        return self._energy
+
     @property
     def frames(self) -> typing.Union[None, tuple]:
         """return tuple of frames. Frames contains """