From 26709885687c782ba30ecbc7a0685cfc0eff55ff Mon Sep 17 00:00:00 2001
From: Stefan Wunsch <stefan.wunsch@cern.ch>
Date: Wed, 13 Mar 2019 16:10:03 +0100
Subject: [PATCH] [PyROOT] Improve documentation of data pointer for array
interface
---
bindings/pyroot/src/Pythonize.cxx | 4 +++-
.../PyROOT/python/ROOT/pythonization/_rvec.py | 4 +++-
2 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/bindings/pyroot/src/Pythonize.cxx b/bindings/pyroot/src/Pythonize.cxx
index 483cbfeddab..bd73790b141 100644
--- a/bindings/pyroot/src/Pythonize.cxx
+++ b/bindings/pyroot/src/Pythonize.cxx
@@ -2334,7 +2334,9 @@ namespace {
// Pointer
auto ptr = reinterpret_cast<unsigned long long>(cobj->data());
- if (cobj->empty()) ptr = 1; // Numpy breaks for data pointer of 0 even though the array is empty.
+ // Numpy breaks for data pointer of 0 even though the array is empty.
+ // We set the pointer to 1 but the value itself is arbitrary and never accessed.
+ if (cobj->empty()) ptr = 1;
auto pyptr = PyLong_FromUnsignedLongLong(ptr);
auto pydata = PyTuple_Pack(2, pyptr, Py_False);
PyDict_SetItemString(dict, "data", pydata);
diff --git a/bindings/pyroot_experimental/PyROOT/python/ROOT/pythonization/_rvec.py b/bindings/pyroot_experimental/PyROOT/python/ROOT/pythonization/_rvec.py
index 612c33370bb..aa1c6ac6ca5 100644
--- a/bindings/pyroot_experimental/PyROOT/python/ROOT/pythonization/_rvec.py
+++ b/bindings/pyroot_experimental/PyROOT/python/ROOT/pythonization/_rvec.py
@@ -33,7 +33,9 @@ def get_array_interface(self):
dtype_size = GetSizeOfType(dtype)
endianess = GetEndianess()
size = self.size()
- if self.empty(): # Numpy sees a null pointer as error even though the data is never accessed.
+ # Numpy breaks for data pointer of 0 even though the array is empty.
+ # We set the pointer to 1 but the value itself is arbitrary and never accessed.
+ if self.empty():
pointer = 1
else:
pointer = GetVectorDataPointer(self, cppname)
--
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