[Python] Correctly manage NumPy dependencey in pythonization tests

The dependency on Python libraries like NumPy needs to be declared in
the CMakeLists.txt, such that the test gets disabled when the library is
not available.

In some cases, the dependency on NumPy could be avoided by using the
builtin "array" library.

Author: guitargeek

bindings/pyroot/pythonizations/python/ROOT/_pythonization/_roofit/_rooglobalfunc.py

@@ -229,7 +229,6 @@ def _bindFunctionOrPdf(name, func, is_rooabspdf, *variables):
     """
 
     import ROOT
-    import numpy as np
 
     # use the C++ version if dealing with C++ function
     if "cppyy" in repr(type(func)):
@@ -245,10 +244,13 @@ def __init__(self, name, title, *variables):
             super(RooPyBindDerived, self).__init__(name, title, ROOT.RooArgList(*variables))
 
         def evaluate(self):
+            import numpy as np
+
             inputs = [np.array([v.getVal()]) for v in self.varlist()]
             return func(*inputs)[0]
 
         def doEvalPy(self, ctx):
+            import numpy as np
 
             def span_to_numpy(sp):
                 return np.frombuffer(sp.data(), dtype=np.float64, count=sp.size())

bindings/pyroot/pythonizations/python/ROOT/_pythonization/_th1.py

@@ -199,6 +199,13 @@ def _FillWithNumpyArray(self, *args):
     Raises:
     - ValueError: If weights length doesn't match data length
     """
+    import collections.abc
+
+    # If the first argument has no len() method, we don't even need to consider
+    # the array code path.
+    if not isinstance(args[0], collections.abc.Sized):
+       return self._Fill(*args)
+
     import numpy as np
 
     if args and isinstance(args[0], np.ndarray):

bindings/pyroot/pythonizations/test/CMakeLists.txt

@@ -117,7 +117,7 @@ endif()
 if (dataframe)
     ROOT_ADD_PYUNITTEST(pyroot_rdfdescription rdfdescription.py)
 
-    ROOT_ADD_PYUNITTEST(pyroot_pyz_rdataframe_misc rdataframe_misc.py)
+    ROOT_ADD_PYUNITTEST(pyroot_pyz_rdataframe_misc rdataframe_misc.py PYTHON_DEPS numpy)
 endif()
 
 # SOFIE-GNN pythonizations
@@ -139,7 +139,7 @@ if (tmva AND dataframe)
 endif()
 
 # Passing Python callables to ROOT.TF
-ROOT_ADD_PYUNITTEST(pyroot_pyz_tf_pycallables tf_pycallables.py)
+ROOT_ADD_PYUNITTEST(pyroot_pyz_tf_pycallables tf_pycallables.py PYTHON_DEPS numpy)
 
 if(roofit)
 

bindings/pyroot/pythonizations/test/rdataframe_misc.py

@@ -1,11 +1,11 @@
-import cppyy
+import array
+import os
 import platform
 import unittest
-import numpy
-import os
 
 import ROOT
 
+
 class DatasetContext:
     """A helper class to create the dataset for the tutorial below."""
 
@@ -22,8 +22,8 @@ def __init__(self):
             with ROOT.TFile(filename, "RECREATE") as f:
                 t = ROOT.TTree(self.treename, self.treename)
 
-                x = numpy.array([0], dtype=int)
-                y = numpy.array([0], dtype=int)
+                x = array.array("i", [0])
+                y = array.array("i", [0])
                 t.Branch("x", x, "x/I")
                 t.Branch("y", y, "y/I")
 
@@ -69,7 +69,7 @@ def test_empty_filenames(self):
 
             # When passing explicitly the vector of strings, type dispatching will not be necessary
             # and the real C++ exception will immediately surface
-            with self.assertRaisesRegex(cppyy.gbl.std.invalid_argument, "RDataFrame: empty list of input files."):
+            with self.assertRaisesRegex(ROOT.std.invalid_argument, "RDataFrame: empty list of input files."):
                 ROOT.RDataFrame("events", ROOT.std.vector[ROOT.std.string]())
 
             with self.assertRaisesRegex(TypeError, "RDataFrame: empty list of input files."):
@@ -110,6 +110,8 @@ def test_ttree_ownership(self):
             return
 
         with DatasetContext() as dataset:
+            import numpy
+
             rdf = self._get_rdf(dataset)
 
             npy_dict = rdf.AsNumpy()

bindings/pyroot/pythonizations/test/stl_vector.py

@@ -1,7 +1,8 @@
+import array
+import random
 import unittest
+
 import ROOT
-import random
-import numpy as np
 
 
 class STL_vector(unittest.TestCase):
@@ -55,9 +56,7 @@ def test_tree_with_containers(self):
         tree = ROOT.TTree("tree", "Tree with std::vector")
 
         # list of random arrays with lengths between 0 and 5 (0 is always included)
-        entries_to_fill = [
-            np.array([random.uniform(10, 20) for _ in range(n % 5)]) for n in range(100)
-        ]
+        entries_to_fill = [array.array("f", [random.uniform(10, 20) for _ in range(n % 5)]) for n in range(100)]
 
         # Create variables to store std::vector elements
         entry_root = ROOT.std.vector(float)()
@@ -76,12 +75,14 @@ def test_tree_with_containers(self):
 
         for i in range(tree.GetEntries()):
             tree.GetEntry(i)
-            entry_numpy = entries_to_fill[i]
-            entry_python_list = list(entry_root)
+            entry_array = entries_to_fill[i]
+
+            self.assertEqual(len(entry_array), len(entry_root))
+
+            self.assertEqual(bool(list(entry_root)), bool(entry_root))  # numpy arrays cannot be converted to bool
 
-            self.assertEqual(len(entry_numpy), len(entry_root))
-            self.assertEqual(bool(entry_python_list), bool(entry_root))  # numpy arrays cannot be converted to bool
-            np.testing.assert_allclose(entry_numpy, np.array(entry_root), rtol=1e-5)
+            for entry_array_i, entry_root_i in zip(entry_array, entry_root):
+                self.assertEqual(entry_array_i, entry_root_i)
 
 
 if __name__ == '__main__':

bindings/pyroot/pythonizations/test/ttree_branch_attr.py

@@ -2,8 +2,6 @@
 
 import ROOT
 
-import numpy as np
-
 
 class TTreeBranchAttr(unittest.TestCase):
     """

tutorials/CMakeLists.txt

@@ -890,10 +890,16 @@ if(ROOT_pyroot_FOUND)
   file(GLOB requires_numpy   RELATIVE ${CMAKE_CURRENT_SOURCE_DIR}
       analysis/dataframe/df026_AsNumpyArrays.py
       analysis/dataframe/df032_RDFFromNumpy.py
+      math/fit/NumericalMinimization.py
       math/fit/combinedFit.py
+      math/fit/fitConvolution.py
       math/fit/multifit.py
-      math/fit/NumericalMinimization.py
-      roofit/roofit/rf409_NumPyPandasToRooFit.py)
+      math/pdf/pdf012_tStudent.py
+      roofit/roofit/rf102_dataimport.py
+      roofit/roofit/rf401_importttreethx.py
+      roofit/roofit/rf409_NumPyPandasToRooFit.py
+      roofit/roofit/rf617_simulation_based_inference_multidimensional.py
+  )
   file(GLOB requires_numba   RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} analysis/dataframe/df038_NumbaDeclare.py)
   file(GLOB requires_pandas  RELATIVE ${CMAKE_CURRENT_SOURCE_DIR}
       analysis/dataframe/df026_AsNumpyArrays.py

tutorials/analysis/dataframe/df036_missingBranches.py

@@ -12,9 +12,10 @@
 #
 # \date September 2024
 # \author Vincenzo Eduardo Padulano (CERN)
+import array
 import os
+
 import ROOT
-import numpy
 
 
 class DatasetContext:
@@ -31,8 +32,8 @@ class DatasetContext:
     def __init__(self):
         with ROOT.TFile(self.filenames[0], "RECREATE") as f:
             t = ROOT.TTree(self.treenames[0], self.treenames[0])
-            x = numpy.array([0], dtype=int)
-            y = numpy.array([0], dtype=int)
+            x = array.array('i', [0]) # any array can also be a numpy array
+            y = array.array('i', [0])
             t.Branch("x", x, "x/I")
             t.Branch("y", y, "y/I")
 
@@ -45,7 +46,7 @@ def __init__(self):
 
         with ROOT.TFile(self.filenames[1], "RECREATE") as f:
             t = ROOT.TTree(self.treenames[1], self.treenames[1])
-            y = numpy.array([0], dtype=int)
+            y = array.array('i', [0]) # any array can also be a numpy array
             t.Branch("y", y, "y/I")
 
             for i in range(1, self.nentries + 1):
@@ -56,7 +57,7 @@ def __init__(self):
 
         with ROOT.TFile(self.filenames[2], "RECREATE") as f:
             t = ROOT.TTree(self.treenames[2], self.treenames[2])
-            x = numpy.array([0], dtype=int)
+            x = array.array('i', [0]) # any array can also be a numpy array
             t.Branch("x", x, "x/I")
 
             for i in range(1, self.nentries + 1):

tutorials/analysis/dataframe/df037_TTreeEventMatching.py

@@ -13,9 +13,10 @@
 #
 # \date September 2024
 # \author Vincenzo Eduardo Padulano (CERN)
+import array
 import os
+
 import ROOT
-import numpy
 
 
 class DatasetContext:
@@ -31,8 +32,8 @@ class DatasetContext:
     def __init__(self):
         with ROOT.TFile(self.main_file, "RECREATE") as f:
             main_tree = ROOT.TTree(self.main_tree_name, self.main_tree_name)
-            idx = numpy.array([0], dtype=int)
-            x = numpy.array([0], dtype=int)
+            idx = array.array('i', [0]) # any array can also be a numpy array
+            x = array.array('i', [0])
             main_tree.Branch("idx", idx, "idx/I")
             main_tree.Branch("x", x, "x/I")
 
@@ -51,8 +52,8 @@ def __init__(self):
         # The first auxiliary file has matching indices 1 and 2, but not 3
         with ROOT.TFile(self.aux_file_1, "RECREATE") as f:
             aux_tree_1 = ROOT.TTree(self.aux_tree_name_1, self.aux_tree_name_1)
-            idx = numpy.array([0], dtype=int)
-            y = numpy.array([0], dtype=int)
+            idx = array.array('i', [0]) # any array can also be a numpy array
+            y = array.array('i', [0])
             aux_tree_1.Branch("idx", idx, "idx/I")
             aux_tree_1.Branch("y", y, "y/I")
 
@@ -68,8 +69,8 @@ def __init__(self):
         # The second auxiliary file has matching indices 1 and 3, but not 2
         with ROOT.TFile(self.aux_file_2, "RECREATE") as f:
             aux_tree_2 = ROOT.TTree(self.aux_tree_name_2, self.aux_tree_name_2)
-            idx = numpy.array([0], dtype=int)
-            z = numpy.array([0], dtype=int)
+            idx = array.array('i', [0]) # any array can also be a numpy array
+            z = array.array('i', [0])
             aux_tree_2.Branch("idx", idx, "idx/I")
             aux_tree_2.Branch("z", z, "z/I")
 

tutorials/roofit/roostats/StandardHypoTestDemo.py

@@ -28,9 +28,9 @@
 #
 # \author Lorenzo Moneta (C++ version), and P. P. (Python translation)
 
+import array
 from warnings import warn
 from gc import collect
-import numpy as np
 
 import ROOT
 
@@ -396,8 +396,8 @@ def StandardHypoTestDemo(
         htExp = ROOT.RooStats.HypoTestResult("Expected Result")
         htExp.Append(htr)
         # find quantiles in alt (S+B) distribution
-        p = np.array([i for i in range(5)], dtype=float)
-        q = np.array([0.5 for i in range(5)], dtype=float)
+        p = array.array('d', [i for i in range(5)])
+        q = array.array('d', [0.5 for i in range(5)])
         for i in range(5):
             sig = -2 + i
             p[i] = ROOT.Math.normal_cdf(sig, 1)