WIP: Try lazy loading scipp converter

Author: franzpoeschel

CMakeLists.txt

@@ -665,6 +665,8 @@ if(openPMD_HAVE_PYTHON)
         __init__.py DaskArray.py DaskDataFrame.py DataFrame.py
         ls/__init__.py   ls/__main__.py
         pipe/__init__.py pipe/__main__.py
+        scipp/__init__.py scipp/loader.py scipp/mesh_loader.py scipp/utils.py
+        ScippLazyInit.py
     )
 endif()
 
@@ -720,6 +722,7 @@ set(openPMD_PYTHON_EXAMPLE_NAMES
     11_particle_dataframe
     12_span_write
     13_write_dynamic_configuration
+    15_scipp_loader
 )
 
 if(openPMD_USE_INVASIVE_TESTS)

examples/15_scipp_loader.py

@@ -0,0 +1,9 @@
+import openpmd_api as pmd
+
+
+def main():
+    series = pmd.Series("./out.bp5", pmd.Access.read_only)
+    scipp_loader = series.to_scipp()
+
+if __name__ == "__main__":
+    main()

src/binding/python/openpmd_api/ScippLazyInit.py

@@ -0,0 +1,8 @@
+def series_to_scipp(series):
+
+    import scipp
+
+    from .scipp import DataLoader
+
+    dl = DataLoader(series)
+    return dl

src/binding/python/openpmd_api/__init__.py

@@ -3,6 +3,7 @@
 from .DaskDataFrame import particles_to_daskdataframe
 from .DataFrame import (iterations_to_cudf, iterations_to_dataframe,
                         particles_to_dataframe)
+from .ScippLazyInit import series_to_scipp
 from .openpmd_api_cxx import *  # noqa
 
 __version__ = cxx.__version__
@@ -16,6 +17,7 @@
 Record_Component.to_dask_array = record_component_to_daskarray  # noqa
 Series.to_df = iterations_to_dataframe  # noqa
 Series.to_cudf = iterations_to_cudf  # noqa
+Series.to_scipp = series_to_scipp
 
 # TODO remove in future versions (deprecated)
 Access_Type = Access  # noqa

src/binding/python/openpmd_api/scipp/loader.py

@@ -61,7 +61,7 @@ class DataLoader:
 
     """
 
-    def __init__(self, path):
+    def __init__(self, series):
         """Initialize the DataLoader with an openPMD series from the specified file path.
 
         :param path: The file path to the openPMD data file.
@@ -71,13 +71,13 @@ def __init__(self, path):
         and the `iterations` attribute as a Scipp dataset containing iteration IDs
         and their corresponding times.
         """
-        self.series = pmd.Series(str(path), pmd.Access.read_only)
+        self.series = series
         self.iterations = get_iterations(self.series)
 
     def get_field(
         self,
         field,
-        component=pmd.Mesh_Record_Component.SCALAR,
+        component=None,
         time=None,
         iteration=None,
         relay=False,

src/binding/python/openpmd_api/scipp/mesh_loader.py

@@ -8,7 +8,6 @@
 """
 
 import numpy as np
-import openpmd_api as pmd
 import scipp as sc
 
 from .utils import _unit_dimension_to_scipp
@@ -135,7 +134,7 @@ def load_data(self):
         return data_array
 
 
-def get_field_data_relay(series, iteration, field, component=pmd.Mesh_Record_Component.SCALAR):
+def get_field_data_relay(series, iteration, field, component=None):
     """Get openPMD mesh as a data relay.
 
     Create a DataRelay object for a specified field and component in an openPMD series.
@@ -152,7 +151,7 @@ def get_field_data_relay(series, iteration, field, component=pmd.Mesh_Record_Com
     :rtype: DataRelay
     """
     record = series.iterations[iteration].meshes[field]
-    rc = record[component]
+    rc = record[component] if component else record
     dims = record.axis_labels
     time = (series.iterations[iteration].time + record.time_offset) * series.iterations[
         iteration
@@ -184,7 +183,7 @@ def get_field_data_relay(series, iteration, field, component=pmd.Mesh_Record_Com
     )
 
 
-def get_field(series, iteration, field, component=pmd.Mesh_Record_Component.SCALAR):
+def get_field(series, iteration, field, component=None):
     """Retrieve and load openPMD mesh data without slicing.
 
     This function creates a DataRelay object for a specified field and component in an openPMD