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pocketpy/3rd/numpy/include/xtensor/xmanipulation.hpp
Anurag Bhat 86b4fc623c
Merge numpy to pocketpy (#303) 
* Merge numpy to pocketpy

* Add CI

* Fix CI
2024-09-02 16:22:41 +08:00

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/***************************************************************************
* Copyright (c) Johan Mabille, Sylvain Corlay and Wolf Vollprecht *
* Copyright (c) QuantStack *
* *
* Distributed under the terms of the BSD 3-Clause License. *
* *
* The full license is in the file LICENSE, distributed with this software. *
****************************************************************************/
#ifndef XTENSOR_MANIPULATION_HPP
#define XTENSOR_MANIPULATION_HPP
#include <algorithm>
#include <utility>
#include <xtl/xcompare.hpp>
#include <xtl/xsequence.hpp>
#include "xbuilder.hpp"
#include "xexception.hpp"
#include "xrepeat.hpp"
#include "xstrided_view.hpp"
#include "xtensor_config.hpp"
#include "xutils.hpp"
namespace xt
{
/**
* @defgroup xt_xmanipulation
*/
namespace check_policy
{
struct none
{
};
struct full
{
};
}
template <class E>
auto transpose(E&& e) noexcept;
template <class E, class S, class Tag = check_policy::none>
auto transpose(E&& e, S&& permutation, Tag check_policy = Tag());
template <class E>
auto swapaxes(E&& e, std::ptrdiff_t axis1, std::ptrdiff_t axis2);
template <layout_type L = XTENSOR_DEFAULT_TRAVERSAL, class E>
auto ravel(E&& e);
template <layout_type L = XTENSOR_DEFAULT_TRAVERSAL, class E>
auto flatten(E&& e);
template <layout_type L, class T>
auto flatnonzero(const T& arr);
template <class E>
auto trim_zeros(E&& e, const std::string& direction = "fb");
template <class E>
auto squeeze(E&& e);
template <class E, class S, class Tag = check_policy::none, std::enable_if_t<!xtl::is_integral<S>::value, int> = 0>
auto squeeze(E&& e, S&& axis, Tag check_policy = Tag());
template <class E>
auto expand_dims(E&& e, std::size_t axis);
template <std::size_t N, class E>
auto atleast_Nd(E&& e);
template <class E>
auto atleast_1d(E&& e);
template <class E>
auto atleast_2d(E&& e);
template <class E>
auto atleast_3d(E&& e);
template <class E>
auto split(E& e, std::size_t n, std::size_t axis = 0);
template <class E>
auto hsplit(E& e, std::size_t n);
template <class E>
auto vsplit(E& e, std::size_t n);
template <class E>
auto flip(E&& e);
template <class E>
auto flip(E&& e, std::size_t axis);
template <std::ptrdiff_t N = 1, class E>
auto rot90(E&& e, const std::array<std::ptrdiff_t, 2>& axes = {0, 1});
template <class E>
auto roll(E&& e, std::ptrdiff_t shift);
template <class E>
auto roll(E&& e, std::ptrdiff_t shift, std::ptrdiff_t axis);
template <class E>
auto repeat(E&& e, std::size_t repeats, std::size_t axis);
template <class E>
auto repeat(E&& e, const std::vector<std::size_t>& repeats, std::size_t axis);
template <class E>
auto repeat(E&& e, std::vector<std::size_t>&& repeats, std::size_t axis);
/****************************
* transpose implementation *
****************************/
namespace detail
{
inline layout_type transpose_layout_noexcept(layout_type l) noexcept
{
layout_type result = l;
if (l == layout_type::row_major)
{
result = layout_type::column_major;
}
else if (l == layout_type::column_major)
{
result = layout_type::row_major;
}
return result;
}
inline layout_type transpose_layout(layout_type l)
{
if (l != layout_type::row_major && l != layout_type::column_major)
{
XTENSOR_THROW(transpose_error, "cannot compute transposed layout of dynamic layout");
}
return transpose_layout_noexcept(l);
}
template <class E, class S>
inline auto transpose_impl(E&& e, S&& permutation, check_policy::none)
{
if (sequence_size(permutation) != e.dimension())
{
XTENSOR_THROW(transpose_error, "Permutation does not have the same size as shape");
}
// permute stride and shape
using shape_type = xindex_type_t<typename std::decay_t<E>::shape_type>;
shape_type temp_shape;
resize_container(temp_shape, e.shape().size());
using strides_type = get_strides_t<shape_type>;
strides_type temp_strides;
resize_container(temp_strides, e.strides().size());
using size_type = typename std::decay_t<E>::size_type;
for (std::size_t i = 0; i < e.shape().size(); ++i)
{
if (std::size_t(permutation[i]) >= e.dimension())
{
XTENSOR_THROW(transpose_error, "Permutation contains wrong axis");
}
size_type perm = static_cast<size_type>(permutation[i]);
temp_shape[i] = e.shape()[perm];
temp_strides[i] = e.strides()[perm];
}
layout_type new_layout = layout_type::dynamic;
if (std::is_sorted(std::begin(permutation), std::end(permutation)))
{
// keep old layout
new_layout = e.layout();
}
else if (std::is_sorted(std::begin(permutation), std::end(permutation), std::greater<>()))
{
new_layout = transpose_layout_noexcept(e.layout());
}
return strided_view(
std::forward<E>(e),
std::move(temp_shape),
std::move(temp_strides),
get_offset<XTENSOR_DEFAULT_LAYOUT>(e),
new_layout
);
}
template <class E, class S>
inline auto transpose_impl(E&& e, S&& permutation, check_policy::full)
{
// check if axis appears twice in permutation
for (std::size_t i = 0; i < sequence_size(permutation); ++i)
{
for (std::size_t j = i + 1; j < sequence_size(permutation); ++j)
{
if (permutation[i] == permutation[j])
{
XTENSOR_THROW(transpose_error, "Permutation contains axis more than once");
}
}
}
return transpose_impl(std::forward<E>(e), std::forward<S>(permutation), check_policy::none());
}
template <class E, class S, class X, std::enable_if_t<has_data_interface<std::decay_t<E>>::value>* = nullptr>
inline void compute_transposed_strides(E&& e, const S&, X& strides)
{
std::copy(e.strides().crbegin(), e.strides().crend(), strides.begin());
}
template <class E, class S, class X, std::enable_if_t<!has_data_interface<std::decay_t<E>>::value>* = nullptr>
inline void compute_transposed_strides(E&&, const S& shape, X& strides)
{
// In the case where E does not have a data interface, the transposition
// makes use of a flat storage adaptor that has layout XTENSOR_DEFAULT_TRAVERSAL
// which should be the one inverted.
layout_type l = transpose_layout(XTENSOR_DEFAULT_TRAVERSAL);
compute_strides(shape, l, strides);
}
}
/**
* Returns a transpose view by reversing the dimensions of xexpression e
*
* @ingroup xt_xmanipulation
* @param e the input expression
*/
template <class E>
inline auto transpose(E&& e) noexcept
{
using shape_type = xindex_type_t<typename std::decay_t<E>::shape_type>;
shape_type shape;
resize_container(shape, e.shape().size());
std::copy(e.shape().crbegin(), e.shape().crend(), shape.begin());
get_strides_t<shape_type> strides;
resize_container(strides, e.shape().size());
detail::compute_transposed_strides(e, shape, strides);
layout_type new_layout = detail::transpose_layout_noexcept(e.layout());
return strided_view(
std::forward<E>(e),
std::move(shape),
std::move(strides),
detail::get_offset<XTENSOR_DEFAULT_TRAVERSAL>(e),
new_layout
);
}
/**
* Returns a transpose view by permuting the xexpression e with @p permutation.
*
* @ingroup xt_xmanipulation
* @param e the input expression
* @param permutation the sequence containing permutation
* @param check_policy the check level (check_policy::full() or check_policy::none())
* @tparam Tag selects the level of error checking on permutation vector defaults to check_policy::none.
*/
template <class E, class S, class Tag>
inline auto transpose(E&& e, S&& permutation, Tag check_policy)
{
return detail::transpose_impl(std::forward<E>(e), std::forward<S>(permutation), check_policy);
}
/// @cond DOXYGEN_INCLUDE_SFINAE
template <class E, class I, std::size_t N, class Tag = check_policy::none>
inline auto transpose(E&& e, const I (&permutation)[N], Tag check_policy = Tag())
{
return detail::transpose_impl(std::forward<E>(e), permutation, check_policy);
}
/// @endcond
/*****************************
* swapaxes implementation *
*****************************/
namespace detail
{
template <class S>
inline S swapaxes_perm(std::size_t dim, std::ptrdiff_t axis1, std::ptrdiff_t axis2)
{
const std::size_t ax1 = normalize_axis(dim, axis1);
const std::size_t ax2 = normalize_axis(dim, axis2);
auto perm = xtl::make_sequence<S>(dim, 0);
using id_t = typename S::value_type;
std::iota(perm.begin(), perm.end(), id_t(0));
perm[ax1] = ax2;
perm[ax2] = ax1;
return perm;
}
}
/**
* Return a new expression with two axes interchanged.
*
* The two axis parameter @p axis and @p axis2 are interchangable.
*
* @ingroup xt_xmanipulation
* @param e The input expression
* @param axis1 First axis to swap
* @param axis2 Second axis to swap
*/
template <class E>
inline auto swapaxes(E&& e, std::ptrdiff_t axis1, std::ptrdiff_t axis2)
{
const auto dim = e.dimension();
check_axis_in_dim(axis1, dim, "Parameter axis1");
check_axis_in_dim(axis2, dim, "Parameter axis2");
using strides_t = get_strides_t<typename std::decay_t<E>::shape_type>;
return transpose(std::forward<E>(e), detail::swapaxes_perm<strides_t>(dim, axis1, axis2));
}
/*****************************
* moveaxis implementation *
*****************************/
namespace detail
{
template <class S>
inline S moveaxis_perm(std::size_t dim, std::ptrdiff_t src, std::ptrdiff_t dest)
{
using id_t = typename S::value_type;
const std::size_t src_norm = normalize_axis(dim, src);
const std::size_t dest_norm = normalize_axis(dim, dest);
// Initializing to src_norm handles case where `dest == -1` and the loop
// does not go check `perm_idx == dest_norm` a `dim+1`th time.
auto perm = xtl::make_sequence<S>(dim, src_norm);
id_t perm_idx = 0;
for (id_t i = 0; xtl::cmp_less(i, dim); ++i)
{
if (xtl::cmp_equal(perm_idx, dest_norm))
{
perm[perm_idx] = src_norm;
++perm_idx;
}
if (xtl::cmp_not_equal(i, src_norm))
{
perm[perm_idx] = i;
++perm_idx;
}
}
return perm;
}
}
/**
* Return a new expression with an axis move to a new position.
*
* @ingroup xt_xmanipulation
* @param e The input expression
* @param src Original position of the axis to move
* @param dest Destination position for the original axis.
*/
template <class E>
inline auto moveaxis(E&& e, std::ptrdiff_t src, std::ptrdiff_t dest)
{
const auto dim = e.dimension();
check_axis_in_dim(src, dim, "Parameter src");
check_axis_in_dim(dest, dim, "Parameter dest");
using strides_t = get_strides_t<typename std::decay_t<E>::shape_type>;
return xt::transpose(std::forward<E>(e), detail::moveaxis_perm<strides_t>(e.dimension(), src, dest));
}
/************************************
* ravel and flatten implementation *
************************************/
namespace detail
{
template <class E, layout_type L>
struct expression_iterator_getter
{
using iterator = decltype(std::declval<E>().template begin<L>());
using const_iterator = decltype(std::declval<E>().template cbegin<L>());
inline static iterator begin(E& e)
{
return e.template begin<L>();
}
inline static const_iterator cbegin(E& e)
{
return e.template cbegin<L>();
}
inline static auto size(E& e)
{
return e.size();
}
};
}
/**
* Return a flatten view of the given expression. No copy is made.
*
* @ingroup xt_xmanipulation
* @param e the input expression
* @tparam L the layout used to read the elements of e.
* If no parameter is specified, XTENSOR_DEFAULT_TRAVERSAL is used.
* @tparam E the type of the expression
*/
template <layout_type L, class E>
inline auto ravel(E&& e)
{
using iterator = decltype(e.template begin<L>());
using iterator_getter = detail::expression_iterator_getter<std::remove_reference_t<E>, L>;
auto size = e.size();
auto adaptor = make_xiterator_adaptor(std::forward<E>(e), iterator_getter());
constexpr layout_type layout = std::is_pointer<iterator>::value ? L : layout_type::dynamic;
using type = xtensor_view<decltype(adaptor), 1, layout, extension::get_expression_tag_t<E>>;
return type(std::move(adaptor), {size});
}
/**
* Return a flatten view of the given expression.
*
* No copy is made.
* This method is equivalent to ravel and is provided for API sameness with NumPy.
*
* @ingroup xt_xmanipulation
* @param e the input expression
* @tparam L the layout used to read the elements of e.
* If no parameter is specified, XTENSOR_DEFAULT_TRAVERSAL is used.
* @tparam E the type of the expression
* @sa ravel
*/
template <layout_type L, class E>
inline auto flatten(E&& e)
{
return ravel<L>(std::forward<E>(e));
}
/**
* Return indices that are non-zero in the flattened version of arr.
*
* Equivalent to ``nonzero(ravel<layout_type>(arr))[0];``
*
* @param arr input array
* @return indices that are non-zero in the flattened version of arr
*/
template <layout_type L, class T>
inline auto flatnonzero(const T& arr)
{
return nonzero(ravel<L>(arr))[0];
}
/*****************************
* trim_zeros implementation *
*****************************/
/**
* Trim zeros at beginning, end or both of 1D sequence.
*
* @ingroup xt_xmanipulation
* @param e input xexpression
* @param direction string of either 'f' for trim from beginning, 'b' for trim from end
* or 'fb' (default) for both.
* @return returns a view without zeros at the beginning and end
*/
template <class E>
inline auto trim_zeros(E&& e, const std::string& direction)
{
XTENSOR_ASSERT_MSG(e.dimension() == 1, "Dimension for trim_zeros has to be 1.");
std::ptrdiff_t begin = 0, end = static_cast<std::ptrdiff_t>(e.size());
auto find_fun = [](const auto& i)
{
return i != 0;
};
if (direction.find("f") != std::string::npos)
{
begin = std::find_if(e.cbegin(), e.cend(), find_fun) - e.cbegin();
}
if (direction.find("b") != std::string::npos && begin != end)
{
end -= std::find_if(e.crbegin(), e.crend(), find_fun) - e.crbegin();
}
return strided_view(std::forward<E>(e), {range(begin, end)});
}
/**************************
* squeeze implementation *
**************************/
/**
* Returns a squeeze view of the given expression.
*
* No copy is made. Squeezing an expression removes dimensions of extent 1.
*
* @ingroup xt_xmanipulation
* @param e the input expression
* @tparam E the type of the expression
*/
template <class E>
inline auto squeeze(E&& e)
{
dynamic_shape<std::size_t> new_shape;
dynamic_shape<std::ptrdiff_t> new_strides;
std::copy_if(
e.shape().cbegin(),
e.shape().cend(),
std::back_inserter(new_shape),
[](std::size_t i)
{
return i != 1;
}
);
decltype(auto) old_strides = detail::get_strides<XTENSOR_DEFAULT_LAYOUT>(e);
std::copy_if(
old_strides.cbegin(),
old_strides.cend(),
std::back_inserter(new_strides),
[](std::ptrdiff_t i)
{
return i != 0;
}
);
return strided_view(std::forward<E>(e), std::move(new_shape), std::move(new_strides), 0, e.layout());
}
namespace detail
{
template <class E, class S>
inline auto squeeze_impl(E&& e, S&& axis, check_policy::none)
{
std::size_t new_dim = e.dimension() - axis.size();
dynamic_shape<std::size_t> new_shape(new_dim);
dynamic_shape<std::ptrdiff_t> new_strides(new_dim);
decltype(auto) old_strides = detail::get_strides<XTENSOR_DEFAULT_LAYOUT>(e);
for (std::size_t i = 0, ix = 0; i < e.dimension(); ++i)
{
if (axis.cend() == std::find(axis.cbegin(), axis.cend(), i))
{
new_shape[ix] = e.shape()[i];
new_strides[ix++] = old_strides[i];
}
}
return strided_view(std::forward<E>(e), std::move(new_shape), std::move(new_strides), 0, e.layout());
}
template <class E, class S>
inline auto squeeze_impl(E&& e, S&& axis, check_policy::full)
{
for (auto ix : axis)
{
if (static_cast<std::size_t>(ix) > e.dimension())
{
XTENSOR_THROW(std::runtime_error, "Axis argument to squeeze > dimension of expression");
}
if (e.shape()[static_cast<std::size_t>(ix)] != 1)
{
XTENSOR_THROW(std::runtime_error, "Trying to squeeze axis != 1");
}
}
return squeeze_impl(std::forward<E>(e), std::forward<S>(axis), check_policy::none());
}
}
/**
* Remove single-dimensional entries from the shape of an xexpression
*
* @ingroup xt_xmanipulation
* @param e input xexpression
* @param axis integer or container of integers, select a subset of single-dimensional
* entries of the shape.
* @param check_policy select check_policy. With check_policy::full(), selecting an axis
* which is greater than one will throw a runtime_error.
*/
template <class E, class S, class Tag, std::enable_if_t<!xtl::is_integral<S>::value, int>>
inline auto squeeze(E&& e, S&& axis, Tag check_policy)
{
return detail::squeeze_impl(std::forward<E>(e), std::forward<S>(axis), check_policy);
}
/// @cond DOXYGEN_INCLUDE_SFINAE
template <class E, class I, std::size_t N, class Tag = check_policy::none>
inline auto squeeze(E&& e, const I (&axis)[N], Tag check_policy = Tag())
{
using arr_t = std::array<I, N>;
return detail::squeeze_impl(
std::forward<E>(e),
xtl::forward_sequence<arr_t, decltype(axis)>(axis),
check_policy
);
}
template <class E, class Tag = check_policy::none>
inline auto squeeze(E&& e, std::size_t axis, Tag check_policy = Tag())
{
return squeeze(std::forward<E>(e), std::array<std::size_t, 1>{axis}, check_policy);
}
/// @endcond
/******************************
* expand_dims implementation *
******************************/
/**
* Expand the shape of an xexpression.
*
* Insert a new axis that will appear at the axis position in the expanded array shape.
* This will return a ``strided_view`` with a ``xt::newaxis()`` at the indicated axis.
*
* @ingroup xt_xmanipulation
* @param e input xexpression
* @param axis axis to expand
* @return returns a ``strided_view`` with expanded dimension
*/
template <class E>
inline auto expand_dims(E&& e, std::size_t axis)
{
xstrided_slice_vector sv(e.dimension() + 1, all());
sv[axis] = newaxis();
return strided_view(std::forward<E>(e), std::move(sv));
}
/*****************************
* atleast_Nd implementation *
*****************************/
/**
* Expand dimensions of xexpression to at least `N`
*
* This adds ``newaxis()`` slices to a ``strided_view`` until
* the dimension of the view reaches at least `N`.
* Note: dimensions are added equally at the beginning and the end.
* For example, a 1-D array of shape (N,) becomes a view of shape (1, N, 1).
*
* @ingroup xt_xmanipulation
* @param e input xexpression
* @tparam N the number of requested dimensions
* @return ``strided_view`` with expanded dimensions
*/
template <std::size_t N, class E>
inline auto atleast_Nd(E&& e)
{
xstrided_slice_vector sv((std::max)(e.dimension(), N), all());
if (e.dimension() < N)
{
std::size_t i = 0;
std::size_t end = static_cast<std::size_t>(std::round(double(N - e.dimension()) / double(N)));
for (; i < end; ++i)
{
sv[i] = newaxis();
}
i += e.dimension();
for (; i < N; ++i)
{
sv[i] = newaxis();
}
}
return strided_view(std::forward<E>(e), std::move(sv));
}
/**
* Expand to at least 1D
*
* @ingroup xt_xmanipulation
* @sa atleast_Nd
*/
template <class E>
inline auto atleast_1d(E&& e)
{
return atleast_Nd<1>(std::forward<E>(e));
}
/**
* Expand to at least 2D
*
* @ingroup xt_xmanipulation
* @sa atleast_Nd
*/
template <class E>
inline auto atleast_2d(E&& e)
{
return atleast_Nd<2>(std::forward<E>(e));
}
/**
* Expand to at least 3D
*
* @ingroup xt_xmanipulation
* @sa atleast_Nd
*/
template <class E>
inline auto atleast_3d(E&& e)
{
return atleast_Nd<3>(std::forward<E>(e));
}
/************************
* split implementation *
************************/
/**
* Split xexpression along axis into subexpressions
*
* This splits an xexpression along the axis in `n` equal parts and
* returns a vector of ``strided_view``.
* Calling split with axis > dimension of e or a `n` that does not result in
* an equal division of the xexpression will throw a runtime_error.
*
* @ingroup xt_xmanipulation
* @param e input xexpression
* @param n number of elements to return
* @param axis axis along which to split the expression
*/
template <class E>
inline auto split(E& e, std::size_t n, std::size_t axis)
{
if (axis >= e.dimension())
{
XTENSOR_THROW(std::runtime_error, "Split along axis > dimension.");
}
std::size_t ax_sz = e.shape()[axis];
xstrided_slice_vector sv(e.dimension(), all());
std::size_t step = ax_sz / n;
std::size_t rest = ax_sz % n;
if (rest)
{
XTENSOR_THROW(std::runtime_error, "Split does not result in equal division.");
}
std::vector<decltype(strided_view(e, sv))> result;
for (std::size_t i = 0; i < n; ++i)
{
sv[axis] = range(i * step, (i + 1) * step);
result.emplace_back(strided_view(e, sv));
}
return result;
}
/**
* Split an xexpression into subexpressions horizontally (column-wise)
*
* This method is equivalent to ``split(e, n, 1)``.
*
* @ingroup xt_xmanipulation
* @param e input xexpression
* @param n number of elements to return
*/
template <class E>
inline auto hsplit(E& e, std::size_t n)
{
return split(e, n, std::size_t(1));
}
/**
* Split an xexpression into subexpressions vertically (row-wise)
*
* This method is equivalent to ``split(e, n, 0)``.
*
* @ingroup xt_xmanipulation
* @param e input xexpression
* @param n number of elements to return
*/
template <class E>
inline auto vsplit(E& e, std::size_t n)
{
return split(e, n, std::size_t(0));
}
/***********************
* flip implementation *
***********************/
/**
* Reverse the order of elements in an xexpression along every axis.
*
* @ingroup xt_xmanipulation
* @param e the input xexpression
* @return returns a view with the result of the flip.
*/
template <class E>
inline auto flip(E&& e)
{
using size_type = typename std::decay_t<E>::size_type;
auto r = flip(e, 0);
for (size_type d = 1; d < e.dimension(); ++d)
{
r = flip(r, d);
}
return r;
}
/**
* Reverse the order of elements in an xexpression along the given axis.
*
* Note: A NumPy/Matlab style `flipud(arr)` is equivalent to `xt::flip(arr, 0)`,
* `fliplr(arr)` to `xt::flip(arr, 1)`.
*
* @ingroup xt_xmanipulation
* @param e the input xexpression
* @param axis the axis along which elements should be reversed
* @return returns a view with the result of the flip
*/
template <class E>
inline auto flip(E&& e, std::size_t axis)
{
using shape_type = xindex_type_t<typename std::decay_t<E>::shape_type>;
shape_type shape;
resize_container(shape, e.shape().size());
std::copy(e.shape().cbegin(), e.shape().cend(), shape.begin());
get_strides_t<shape_type> strides;
decltype(auto) old_strides = detail::get_strides<XTENSOR_DEFAULT_LAYOUT>(e);
resize_container(strides, old_strides.size());
std::copy(old_strides.cbegin(), old_strides.cend(), strides.begin());
strides[axis] *= -1;
std::size_t offset = static_cast<std::size_t>(
static_cast<std::ptrdiff_t>(e.data_offset())
+ old_strides[axis] * (static_cast<std::ptrdiff_t>(e.shape()[axis]) - 1)
);
return strided_view(std::forward<E>(e), std::move(shape), std::move(strides), offset);
}
/************************
* rot90 implementation *
************************/
namespace detail
{
template <std::ptrdiff_t N>
struct rot90_impl;
template <>
struct rot90_impl<0>
{
template <class E>
inline auto operator()(E&& e, const std::array<std::size_t, 2>& /*axes*/)
{
return std::forward<E>(e);
}
};
template <>
struct rot90_impl<1>
{
template <class E>
inline auto operator()(E&& e, const std::array<std::size_t, 2>& axes)
{
using std::swap;
dynamic_shape<std::ptrdiff_t> axes_list(e.shape().size());
std::iota(axes_list.begin(), axes_list.end(), 0);
swap(axes_list[axes[0]], axes_list[axes[1]]);
return transpose(flip(std::forward<E>(e), axes[1]), std::move(axes_list));
}
};
template <>
struct rot90_impl<2>
{
template <class E>
inline auto operator()(E&& e, const std::array<std::size_t, 2>& axes)
{
return flip(flip(std::forward<E>(e), axes[0]), axes[1]);
}
};
template <>
struct rot90_impl<3>
{
template <class E>
inline auto operator()(E&& e, const std::array<std::size_t, 2>& axes)
{
using std::swap;
dynamic_shape<std::ptrdiff_t> axes_list(e.shape().size());
std::iota(axes_list.begin(), axes_list.end(), 0);
swap(axes_list[axes[0]], axes_list[axes[1]]);
return flip(transpose(std::forward<E>(e), std::move(axes_list)), axes[1]);
}
};
}
/**
* Rotate an array by 90 degrees in the plane specified by axes.
*
* Rotation direction is from the first towards the second axis.
*
* @ingroup xt_xmanipulation
* @param e the input xexpression
* @param axes the array is rotated in the plane defined by the axes. Axes must be different.
* @tparam N number of times the array is rotated by 90 degrees. Default is 1.
* @return returns a view with the result of the rotation
*/
template <std::ptrdiff_t N, class E>
inline auto rot90(E&& e, const std::array<std::ptrdiff_t, 2>& axes)
{
auto ndim = static_cast<std::ptrdiff_t>(e.shape().size());
if (axes[0] == axes[1] || std::abs(axes[0] - axes[1]) == ndim)
{
XTENSOR_THROW(std::runtime_error, "Axes must be different");
}
auto norm_axes = forward_normalize<std::array<std::size_t, 2>>(e, axes);
constexpr std::ptrdiff_t n = (4 + (N % 4)) % 4;
return detail::rot90_impl<n>()(std::forward<E>(e), norm_axes);
}
/***********************
* roll implementation *
***********************/
/**
* Roll an expression.
*
* The expression is flatten before shifting, after which the original
* shape is restore. Elements that roll beyond the last position are
* re-introduced at the first. This function does not change the input
* expression.
*
* @ingroup xt_xmanipulation
* @param e the input xexpression
* @param shift the number of places by which elements are shifted
* @return a roll of the input expression
*/
template <class E>
inline auto roll(E&& e, std::ptrdiff_t shift)
{
auto cpy = empty_like(e);
auto flat_size = std::accumulate(
cpy.shape().begin(),
cpy.shape().end(),
1L,
std::multiplies<std::size_t>()
);
while (shift < 0)
{
shift += flat_size;
}
shift %= flat_size;
std::copy(e.begin(), e.end() - shift, std::copy(e.end() - shift, e.end(), cpy.begin()));
return cpy;
}
namespace detail
{
/**
* Algorithm adapted from pythran/pythonic/numpy/roll.hpp
*/
template <class To, class From, class S>
To roll(To to, From from, std::ptrdiff_t shift, std::size_t axis, const S& shape, std::size_t M)
{
std::ptrdiff_t dim = std::ptrdiff_t(shape[M]);
std::ptrdiff_t offset = std::accumulate(
shape.begin() + M + 1,
shape.end(),
std::ptrdiff_t(1),
std::multiplies<std::ptrdiff_t>()
);
if (shape.size() == M + 1)
{
if (axis == M)
{
const auto split = from + (dim - shift) * offset;
for (auto iter = split, end = from + dim * offset; iter != end; iter += offset, ++to)
{
*to = *iter;
}
for (auto iter = from, end = split; iter != end; iter += offset, ++to)
{
*to = *iter;
}
}
else
{
for (auto iter = from, end = from + dim * offset; iter != end; iter += offset, ++to)
{
*to = *iter;
}
}
}
else
{
if (axis == M)
{
const auto split = from + (dim - shift) * offset;
for (auto iter = split, end = from + dim * offset; iter != end; iter += offset)
{
to = roll(to, iter, shift, axis, shape, M + 1);
}
for (auto iter = from, end = split; iter != end; iter += offset)
{
to = roll(to, iter, shift, axis, shape, M + 1);
}
}
else
{
for (auto iter = from, end = from + dim * offset; iter != end; iter += offset)
{
to = roll(to, iter, shift, axis, shape, M + 1);
}
}
}
return to;
}
}
/**
* Roll an expression along a given axis.
*
* Elements that roll beyond the last position are re-introduced at the first.
* This function does not change the input expression.
*
* @ingroup xt_xmanipulation
* @param e the input xexpression
* @param shift the number of places by which elements are shifted
* @param axis the axis along which elements are shifted.
* @return a roll of the input expression
*/
template <class E>
inline auto roll(E&& e, std::ptrdiff_t shift, std::ptrdiff_t axis)
{
auto cpy = empty_like(e);
const auto& shape = cpy.shape();
std::size_t saxis = static_cast<std::size_t>(axis);
if (axis < 0)
{
axis += std::ptrdiff_t(cpy.dimension());
}
if (saxis >= cpy.dimension() || axis < 0)
{
XTENSOR_THROW(std::runtime_error, "axis is no within shape dimension.");
}
const auto axis_dim = static_cast<std::ptrdiff_t>(shape[saxis]);
while (shift < 0)
{
shift += axis_dim;
}
detail::roll(cpy.begin(), e.begin(), shift, saxis, shape, 0);
return cpy;
}
/****************************
* repeat implementation *
****************************/
namespace detail
{
template <class E, class R>
inline auto make_xrepeat(E&& e, R&& r, typename std::decay_t<E>::size_type axis)
{
const auto casted_axis = static_cast<typename std::decay_t<E>::size_type>(axis);
if (r.size() != e.shape(casted_axis))
{
XTENSOR_THROW(std::invalid_argument, "repeats must have the same size as the specified axis");
}
return xrepeat<const_xclosure_t<E>, R>(std::forward<E>(e), std::forward<R>(r), axis);
}
}
/**
* Repeat elements of an expression along a given axis.
*
* @ingroup xt_xmanipulation
* @param e the input xexpression
* @param repeats The number of repetition of each elements.
* @p repeats is broadcasted to fit the shape of the given @p axis.
* @param axis the axis along which to repeat the value
* @return an expression which as the same shape as \ref e, except along the given \ref axis
*/
template <class E>
inline auto repeat(E&& e, std::size_t repeats, std::size_t axis)
{
const auto casted_axis = static_cast<typename std::decay_t<E>::size_type>(axis);
std::vector<std::size_t> broadcasted_repeats(e.shape(casted_axis));
std::fill(broadcasted_repeats.begin(), broadcasted_repeats.end(), repeats);
return repeat(std::forward<E>(e), std::move(broadcasted_repeats), axis);
}
/**
* Repeat elements of an expression along a given axis.
*
* @ingroup xt_xmanipulation
* @param e the input xexpression
* @param repeats The number of repetition of each elements.
* The size of @p repeats must match the shape of the given @p axis.
* @param axis the axis along which to repeat the value
*
* @return an expression which as the same shape as \ref e, except along the given \ref axis
*/
template <class E>
inline auto repeat(E&& e, const std::vector<std::size_t>& repeats, std::size_t axis)
{
return detail::make_xrepeat(std::forward<E>(e), repeats, axis);
}
/**
* Repeat elements of an expression along a given axis.
*
* @ingroup xt_xmanipulation
* @param e the input xexpression
* @param repeats The number of repetition of each elements.
* The size of @p repeats must match the shape of the given @p axis.
* @param axis the axis along which to repeat the value
* @return an expression which as the same shape as \ref e, except along the given \ref axis
*/
template <class E>
inline auto repeat(E&& e, std::vector<std::size_t>&& repeats, std::size_t axis)
{
return detail::make_xrepeat(std::forward<E>(e), std::move(repeats), axis);
}
}
#endif
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