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array: add direct data access and indexing methods

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This commit is contained in:
Ivan Smirnov 2016-09-08 21:48:14 +01:00
parent 91b3d681ad
commit f2a0ad5855
1 changed files with 102 additions and 33 deletions
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135
include/pybind11/numpy.h
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@ -26,8 +26,14 @@
#pragma warning(disable: 4127) // warning C4127: Conditional expression is constant
#endif
/* This will be true on all flat address space platforms and allows us to reduce the
whole npy_intp / size_t / Py_intptr_t business down to just size_t for all size
and dimension types (e.g. shape, strides, indexing), instead of inflicting this
upon the library user. */
static_assert(sizeof(size_t) == sizeof(Py_intptr_t), "size_t != Py_intptr_t");
NAMESPACE_BEGIN(pybind11)
namespace detail {
NAMESPACE_BEGIN(detail)
template <typename type, typename SFINAE = void> struct npy_format_descriptor { };
template <typename type> struct is_pod_struct;
@ -141,10 +147,12 @@ private:
return api;
}
};
}
NAMESPACE_END(detail)
#define PyArray_GET_(ptr, attr) (reinterpret_cast<::pybind11::detail::PyArray_Proxy*>(ptr)->attr)
#define PyArrayDescr_GET_(ptr, attr) (reinterpret_cast<::pybind11::detail::PyArrayDescr_Proxy*>(ptr)->attr)
#define PyArray_GET_(ptr, attr) \
(reinterpret_cast<::pybind11::detail::PyArray_Proxy*>(ptr)->attr)
#define PyArrayDescr_GET_(ptr, attr) \
(reinterpret_cast<::pybind11::detail::PyArrayDescr_Proxy*>(ptr)->attr)
#define PyArray_CHKFLAGS_(ptr, flag) \
(flag == (reinterpret_cast<::pybind11::detail::PyArray_Proxy*>(ptr)->flags & flag))
@ -250,7 +258,7 @@ public:
};
array(const pybind11::dtype& dt, const std::vector<size_t>& shape,
const std::vector<size_t>& strides, void *ptr = nullptr) {
const std::vector<size_t>& strides, const void *ptr = nullptr) {
auto& api = detail::npy_api::get();
auto ndim = shape.size();
if (shape.size() != strides.size())
@ -258,7 +266,7 @@ public:
auto descr = dt;
object tmp(api.PyArray_NewFromDescr_(
api.PyArray_Type_, descr.release().ptr(), (int) ndim, (Py_intptr_t *) shape.data(),
(Py_intptr_t *) strides.data(), ptr, 0, nullptr), false);
(Py_intptr_t *) strides.data(), const_cast<void *>(ptr), 0, nullptr), false);
if (!tmp)
pybind11_fail("NumPy: unable to create array!");
if (ptr)
@ -266,20 +274,20 @@ public:
m_ptr = tmp.release().ptr();
}
array(const pybind11::dtype& dt, const std::vector<size_t>& shape, void *ptr = nullptr)
array(const pybind11::dtype& dt, const std::vector<size_t>& shape, const void *ptr = nullptr)
: array(dt, shape, default_strides(shape, dt.itemsize()), ptr) { }
array(const pybind11::dtype& dt, size_t count, void *ptr = nullptr)
array(const pybind11::dtype& dt, size_t count, const void *ptr = nullptr)
: array(dt, std::vector<size_t> { count }, ptr) { }
template<typename T> array(const std::vector<size_t>& shape,
const std::vector<size_t>& strides, T* ptr)
const std::vector<size_t>& strides, const T* ptr)
: array(pybind11::dtype::of<T>(), shape, strides, (void *) ptr) { }
template<typename T> array(const std::vector<size_t>& shape, T* ptr)
template<typename T> array(const std::vector<size_t>& shape, const T* ptr)
: array(shape, default_strides(shape, sizeof(T)), ptr) { }
template<typename T> array(size_t count, T* ptr)
template<typename T> array(size_t count, const T* ptr)
: array(std::vector<size_t> { count }, ptr) { }
array(const buffer_info &info)
@ -312,27 +320,25 @@ public:
/// Dimensions of the array
const size_t* shape() const {
static_assert(sizeof(size_t) == sizeof(Py_intptr_t), "size_t != Py_intptr_t");
return reinterpret_cast<const size_t *>(PyArray_GET_(m_ptr, dimensions));
}
/// Dimension along a given axis
size_t shape(size_t dim) const {
if (dim >= ndim())
pybind11_fail("NumPy: attempted to index shape beyond ndim");
fail_dim_check(dim, "invalid axis");
return shape()[dim];
}
/// Strides of the array
const size_t* strides() const {
static_assert(sizeof(size_t) == sizeof(Py_intptr_t), "size_t != Py_intptr_t");
return reinterpret_cast<const size_t *>(PyArray_GET_(m_ptr, strides));
}
/// Stride along a given axis
size_t strides(size_t dim) const {
if (dim >= ndim())
pybind11_fail("NumPy: attempted to index strides beyond ndim");
fail_dim_check(dim, "invalid axis");
return strides()[dim];
}
@ -346,20 +352,61 @@ public:
return PyArray_CHKFLAGS_(m_ptr, detail::npy_api::NPY_ARRAY_OWNDATA_);
}
/// Direct pointer to contained buffer
const void* data() const {
return reinterpret_cast<const void *>(PyArray_GET_(m_ptr, data));
/// Pointer to the contained data. If index is not provided, points to the
/// beginning of the buffer. May throw if the index would lead to out of bounds access.
template<typename... Ix> const void* data(Ix&&... index) const {
return static_cast<const void *>(PyArray_GET_(m_ptr, data) + offset_at(index...));
}
/// Direct mutable pointer to contained buffer (checks writeable flag)
void* mutable_data() {
if (!writeable())
pybind11_fail("NumPy: cannot get mutable data of a read-only array");
return reinterpret_cast<void *>(PyArray_GET_(m_ptr, data));
/// Mutable pointer to the contained data. If index is not provided, points to the
/// beginning of the buffer. May throw if the index would lead to out of bounds access.
/// May throw if the array is not writeable.
template<typename... Ix> void* mutable_data(Ix&&... index) {
check_writeable();
return static_cast<void *>(PyArray_GET_(m_ptr, data) + offset_at(index...));
}
/// Byte offset from beginning of the array to a given index (full or partial).
/// May throw if the index would lead to out of bounds access.
template<typename... Ix> size_t offset_at(Ix&&... index) const {
if (sizeof...(index) > ndim())
fail_dim_check(sizeof...(index), "too many indices for an array");
return get_byte_offset(index...);
}
size_t offset_at() const { return 0; }
/// Item count from beginning of the array to a given index (full or partial).
/// May throw if the index would lead to out of bounds access.
template<typename... Ix> size_t index_at(Ix&&... index) const {
return offset_at(index...) / itemsize();
}
protected:
template <typename T, typename SFINAE> friend struct detail::npy_format_descriptor;
template<typename, typename> friend struct detail::npy_format_descriptor;
void fail_dim_check(size_t dim, const std::string& msg) const {
throw index_error(msg + ": " + std::to_string(dim) +
" (ndim = " + std::to_string(ndim()) + ")");
}
template<typename... Ix> size_t get_byte_offset(Ix&&... index) const {
const size_t idx[] = { (size_t) index... };
if (!std::equal(idx + 0, idx + sizeof...(index), shape(), std::less<size_t>{})) {
auto mismatch = std::mismatch(idx + 0, idx + sizeof...(index), shape(), std::less<size_t>{});
throw index_error(std::string("index ") + std::to_string(*mismatch.first) +
" is out of bounds for axis " + std::to_string(mismatch.first - idx) +
" with size " + std::to_string(*mismatch.second));
}
return std::inner_product(idx + 0, idx + sizeof...(index), strides(), (size_t) 0);
}
size_t get_byte_offset() const { return 0; }
void check_writeable() const {
if (!writeable())
throw std::runtime_error("array is not writeable");
}
static std::vector<size_t> default_strides(const std::vector<size_t>& shape, size_t itemsize) {
auto ndim = shape.size();
@ -382,23 +429,45 @@ public:
array_t(const buffer_info& info) : array(info) { }
array_t(const std::vector<size_t>& shape, const std::vector<size_t>& strides, T* ptr = nullptr)
array_t(const std::vector<size_t>& shape, const std::vector<size_t>& strides, const T* ptr = nullptr)
: array(shape, strides, ptr) { }
array_t(const std::vector<size_t>& shape, T* ptr = nullptr)
array_t(const std::vector<size_t>& shape, const T* ptr = nullptr)
: array(shape, ptr) { }
array_t(size_t count, T* ptr = nullptr)
array_t(size_t count, const T* ptr = nullptr)
: array(count, ptr) { }
const T* data() const {
return reinterpret_cast<const T *>(PyArray_GET_(m_ptr, data));
constexpr size_t itemsize() const {
return sizeof(T);
}
T* mutable_data() {
if (!writeable())
pybind11_fail("NumPy: cannot get mutable data of a read-only array");
return reinterpret_cast<T *>(PyArray_GET_(m_ptr, data));
template<typename... Ix> size_t index_at(Ix&... index) const {
return offset_at(index...) / itemsize();
}
template<typename... Ix> const T* data(Ix&&... index) const {
return static_cast<const T*>(array::data(index...));
}
template<typename... Ix> T* mutable_data(Ix&&... index) {
return static_cast<T*>(array::mutable_data(index...));
}
// Reference to element at a given index
template<typename... Ix> const T& at(Ix&&... index) const {
if (sizeof...(index) != ndim())
fail_dim_check(sizeof...(index), "index dimension mismatch");
// not using offset_at() / index_at() here so as to avoid another dimension check
return *(static_cast<const T*>(array::data()) + get_byte_offset(index...) / itemsize());
}
// Mutable reference to element at a given index
template<typename... Ix> T& mutable_at(Ix&&... index) {
if (sizeof...(index) != ndim())
fail_dim_check(sizeof...(index), "index dimension mismatch");
// not using offset_at() / index_at() here so as to avoid another dimension check
return *(static_cast<T*>(array::mutable_data()) + get_byte_offset(index...) / itemsize());
}
static bool is_non_null(PyObject *ptr) { return ptr != nullptr; }