Use lazy imports for dask and pandas (#1442)

openPMD · May 23, 2023 · f875c10 · f875c10
1 parent 0687580
commit f875c10
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Showing 3 changed files with 27 additions and 24 deletions.
diff --git a/src/binding/python/openpmd_api/DaskArray.py b/src/binding/python/openpmd_api/DaskArray.py
@@ -9,12 +9,6 @@
 
 import numpy as np
 
-try:
-    from dask.array import from_array
-    found_dask = True
-except ImportError:
-    found_dask = False
-
 
 class DaskRecordComponent:
     # shape, .ndim, .dtype and support numpy-style slicing
@@ -80,6 +74,13 @@ def record_component_to_daskarray(record_component):
         are used internally to parallelize reading
     dask.array : the (potentially distributed) array object created here
     """
+    # Import dask here for a lazy import
+    try:
+        from dask.array import from_array
+        found_dask = True
+    except ImportError:
+        found_dask = False
+
     if not found_dask:
         raise ImportError("dask NOT found. Install dask for Dask DataFrame "
                           "support.")

diff --git a/src/binding/python/openpmd_api/DaskDataFrame.py b/src/binding/python/openpmd_api/DaskDataFrame.py
@@ -7,18 +7,6 @@
 """
 import numpy as np
 
-try:
-    import dask.dataframe as dd
-    from dask.delayed import delayed
-    found_dask = True
-except ImportError:
-    found_dask = False
-try:
-    import pandas  # noqa
-    found_pandas = True
-except ImportError:
-    found_pandas = False
-
 
 def read_chunk_to_df(species, chunk):
     stride = np.s_[chunk.offset[0]:chunk.offset[0]+chunk.extent[0]]
@@ -51,6 +39,19 @@ def particles_to_daskdataframe(particle_species):
         are used internally to parallelize particle processing
     dask.dataframe : the central dataframe object created here
     """
+    # import here for lazy imports
+    try:
+        import dask.dataframe as dd
+        from dask.delayed import delayed
+        found_dask = True
+    except ImportError:
+        found_dask = False
+    try:
+        import pandas  # noqa
+        found_pandas = True
+    except ImportError:
+        found_pandas = False
+
     if not found_dask:
         raise ImportError("dask NOT found. Install dask for Dask DataFrame "
                           "support.")

diff --git a/src/binding/python/openpmd_api/DataFrame.py b/src/binding/python/openpmd_api/DataFrame.py
@@ -9,12 +9,6 @@
 
 import numpy as np
 
-try:
-    import pandas as pd
-    found_pandas = True
-except ImportError:
-    found_pandas = False
-
 
 def particles_to_dataframe(particle_species, slice=None):
     """
@@ -46,6 +40,13 @@ def particles_to_dataframe(particle_species, slice=None):
         are optimal arguments for the slice parameter
     pandas.DataFrame : the central dataframe object created here
     """
+    # import pandas here for a lazy import
+    try:
+        import pandas as pd
+        found_pandas = True
+    except ImportError:
+        found_pandas = False
+
     if not found_pandas:
         raise ImportError("pandas NOT found. Install pandas for DataFrame "
                           "support.")