Make start positioners more generic

src/PyMca5/PyMcaCore/NexusTools.py

@@ -515,7 +515,11 @@ def getStartingPositionersGroup(h5file, path):
     Retrieve the start positioners group associated to a path
     retrieving them from the same entry.
 
-    This method assumes the positioner group is NXentry/NXinstrument/positioners_start.
+    It assumes they are either in:
+
+    - NXentry/NXinstrument/positioners_start or 
+    - NXentry/NXinstrument/positioners or
+    - NXentry/measurement/pre_scan_snapshot
 
     """
     entry_path = getEntryName(path, h5file=h5file)
@@ -528,8 +532,33 @@ def getStartingPositionersGroup(h5file, path):
                 positioners = instrument[key]
                 if not isGroup(positioners):
                     positioners = None
+    if positioners is None:
+        positioners = getPositionersGroup(h5file, path)
     return positioners
 
+def getStartingPositionerValues(h5file, path):
+    """
+    Retrieve the start positioners names, values and units associated to a path
+    retrieving them from the same entry.
+
+    It assumes they are either in:
+
+    - NXentry/NXinstrument/positioners_start or 
+    - NXentry/NXinstrument/positioners or
+    - NXentry/measurement/pre_scan_snapshot
+
+    """
+    nxpositioners = getStartingPositionersGroup(h5file, path)
+    positions = list()
+    if nxpositioners is None:
+        return positions
+    for name, dset in nxpositioners.items():
+        if not isinstance(dset, h5py.Dataset):
+            continue
+        idx = (0,) * dset.ndim
+        positions.append((name, dset[idx], dset.attrs.get("units", "")))
+    return positions
+
 def getMeasurementGroup(h5file, path):
     """
     Retrieve the measurement group associated to a path

src/PyMca5/PyMcaGui/io/hdf5/NexusInfo.py

@@ -1,7 +1,7 @@
 import h5py
 
 from PyMca5.PyMcaGui import PyMcaQt as qt
-from PyMca5.PyMcaCore.NexusTools import getStartingPositionersGroup
+from PyMca5.PyMcaCore.NexusTools import getStartingPositionerValues
 
 from . import HDF5Info
 
@@ -96,15 +96,6 @@ def get_motor_positions(hdf5File, node):
     if not isinstance(nxentry, h5py.Group):
         return dict()
 
-    nxpositioners = getStartingPositionersGroup(hdf5File, nxentry_name)
-    if nxpositioners is None or not isinstance(nxpositioners, h5py.Group):
-        return dict()
-
-    positions = [
-        (name, dset[()], dset.attrs.get("units", ""))
-        for name, dset in nxpositioners.items()
-        if isinstance(dset, h5py.Dataset) and dset.ndim == 0
-    ]
+    positions = getStartingPositionerValues(hdf5File, nxentry_name)
     column_names = "Name", "Value", "Units"
-
     return dict(zip(column_names, zip(*positions)))