Add extraction of NumPy arrays from python::object.

Add functions extractNumPyDoubleArray and createNumPyDoubleArrayLike.

Author: pavoljuhas

srrealmodule/srreal_converters.cpp

@@ -106,6 +106,22 @@ NumPyArray_DoublePtr createNumPyDoubleArray(int dim, const int* sz)
 }
 
 
+/// helper for creating numpy array of the same shape as the argument
+NumPyArray_DoublePtr createNumPyDoubleArrayLike(boost::python::object& obj)
+{
+    PyObject* arr = obj.ptr();
+    int dim = PyArray_NDIM(arr);
+    npy_intp* shape = PyArray_DIMS(arr);
+    // create numpy array
+    boost::python::object rvobj(
+            boost::python::handle<>(
+                PyArray_SimpleNew(dim, shape, PyArray_DOUBLE)));
+    double* rvdata = static_cast<double*>(PyArray_DATA(rvobj.ptr()));
+    NumPyArray_DoublePtr rv(rvobj, rvdata);
+    return rv;
+}
+
+
 /// helper for creating a numpy array view on a double array
 boost::python::object
 createNumPyDoubleView(double* data, int dim, const int* sz)
@@ -248,6 +264,24 @@ extractQuantityType(
 }
 
 
+/// efficient conversion of Python object to a numpy array of doubles
+NumPyArray_DoublePtr extractNumPyDoubleArray(::boost::python::object& obj)
+{
+    PyObject* arr = PyArray_ContiguousFromAny(obj.ptr(), PyArray_DOUBLE, 0, 0);
+    if (!arr)
+    {
+        const char* emsg = "Cannot convert this object to numpy array.";
+        PyErr_SetString(PyExc_TypeError, emsg);
+        boost::python::throw_error_already_set();
+        assert(false);
+    }
+    boost::python::object rvobj((boost::python::handle<>(arr)));
+    double* rvdata = static_cast<double*>(PyArray_DATA(arr));
+    NumPyArray_DoublePtr rv(rvobj, rvdata);
+    return rv;
+}
+
+
 /// extract integer with a support for numpy.int types
 int extractint(boost::python::object obj)
 {

srrealmodule/srreal_converters.hpp

@@ -227,12 +227,19 @@ void fillPyListWithSets(::boost::python::list lst, const T& value)
 /// Type for numpy array object and a raw pointer to its double data
 typedef std::pair<boost::python::object, double*> NumPyArray_DoublePtr;
 
+
 /// helper for creating numpy array of doubles
 NumPyArray_DoublePtr createNumPyDoubleArray(int dim, const int* sz);
 
+
+/// helper for creating numpy array of the same shape as the argument
+NumPyArray_DoublePtr createNumPyDoubleArrayLike(boost::python::object& obj);
+
+
 /// helper for creating numpy views on existing double array
 boost::python::object createNumPyDoubleView(double*, int dim, const int* sz);
 
+
 /// template function for converting iterables to numpy array of doubles
 template <class Iter>
 ::boost::python::object
@@ -296,25 +303,31 @@ convertToNumPyArray(const ::diffpy::srreal::QuantityType& value)
     return convertToNumPyArray(value.begin(), value.end());
 }
 
+
 /// NumPy array view specializations for R3::Vector
 boost::python::object
 viewAsNumPyArray(::diffpy::srreal::R3::Vector&);
 
+
 /// NumPy array view specializations for R3::Matrix
 boost::python::object
 viewAsNumPyArray(::diffpy::srreal::R3::Matrix&);
 
+
 /// Copy possible NumPy array to R3::Vector
 void assignR3Vector(
         ::diffpy::srreal::R3::Vector& dst, boost::python::object& value);
 
+
 /// Copy possible NumPy array to R3::Matrix
 void assignR3Matrix(
         ::diffpy::srreal::R3::Matrix& dst, boost::python::object& value);
 
+
 /// Type for numpy array object and a raw pointer to its double data
 typedef std::pair<boost::python::object, int*> NumPyArray_IntPtr;
 
+
 /// helper for creating numpy array of integers
 NumPyArray_IntPtr createNumPyIntArray(int dim, const int* sz);
 
@@ -361,6 +374,10 @@ extractQuantityType(::boost::python::object obj,
         ::diffpy::srreal::QuantityType& rv);
 
 
+/// efficient conversion of Python object to a numpy array of doubles
+NumPyArray_DoublePtr extractNumPyDoubleArray(::boost::python::object& obj);
+
+
 /// extract integer with a support for numpy.int types
 int extractint(::boost::python::object obj);