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Merged
JohanMabille merged 4 commits into from
Jan 6, 2020
Merged

Add row and col facade for 2 dim container #1876

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67f256e
Add row and col facade for 2 dim container
kolibri91 Jan 1, 2020
d9ba79b
Use XT_ASSERT_THROW instead of ASSERT_THROW
kolibri91 Jan 1, 2020
bcd024c
Add documentation and apply naming conventions
kolibri91 Jan 2, 2020
2cff0e7
Support negative indices for accessing last row/col
kolibri91 Jan 2, 2020
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91 changes: 91 additions & 0 deletions include/xtensor/xview.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -705,6 +705,12 @@ namespace xt
template <class E, class... S>
auto view(E&& e, S&&... slices);

template <class E>
auto row(E&& e, const int index);
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template <class E>
auto col(E&& e, const int index);

/*****************************
* xview_stepper declaration *
*****************************/
Expand Down Expand Up @@ -1661,6 +1667,91 @@ namespace xt
return detail::make_view_impl(std::forward<E>(e), std::make_index_sequence<sizeof...(S)>(), std::forward<S>(slices)...);
}

namespace detail
{
class row_impl
{
public:
template<class E>
static inline auto make(E&& e, const int index)
{
check_dimension(e.shape());
return view(e, index, xt::all());
}

private:
template<class S>
static inline void check_dimension(const S& shape)
{
if (shape.size() != 2)
{
XTENSOR_THROW(std::invalid_argument, "A row can only be accessed on an expression with exact two dimensions");
}
}

template<class T, int N>
static inline void check_dimension(const std::array<T, N>&)
{
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static_assert(N == 2, "A row can only be accessed on an expression with exact two dimensions");
}
};

class column_impl
{
public:
template<class E>
static inline auto make(E&& e, const int index)
{
check_dimension(e.shape());
return view(e, xt::all(), index);
}

private:
template<class S>
static inline void check_dimension(const S& shape)
{
if (shape.size() != 2)
{
XTENSOR_THROW(std::invalid_argument, "A column can only be accessed on an expression with exact two dimensions");
}
}

template<class T, int N>
static inline void check_dimension(const std::array<T, N>&)
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{
static_assert(N == 2, "A column can only be accessed on an expression with exact two dimensions");
}
};
}

/**
* Constructs and returns a row (sliced view) on the specified expression.
* Users should not directly construct the slices but call helper functions
* instead. This function is only allowed on expressions with two dimensions.
* @param e the xexpression to adapt
* @param index 0-based index of the row
* @throws std::invalid_argument if the expression has more than 2 dimensions.
*/
template <class E>
inline auto row(E&& e, int index)
{
return detail::row_impl::make(e, index);
}

/**
* Constructs and returns a column (sliced view) on the specified expression.
* Users should not directly construct the slices but call helper functions
* instead. This function is only allowed on expressions with two dimensions.
* @param e the xexpression to adapt
* @param index 0-based index of the column
* @throws std::invalid_argument if the expression has more than 2 dimensions.
*/
template <class E>
inline auto col(E&& e, int index)
{
return detail::column_impl::make(e, index);
}

/***************
* stepper api *
***************/
Expand Down
132 changes: 132 additions & 0 deletions test/test_xview.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1489,4 +1489,136 @@ namespace xt
EXPECT_FALSE(a(1, 0));
EXPECT_FALSE(a(1, 1));
}

TEST(xview, row_on_2dim_xarray)
{
xt::xarray<int> array{
{ 1, 2 },
{ 3, 4 },
};

const auto row0 = xt::row(array, 0);
const auto row1 = xt::row(array, 1);

EXPECT_EQ(row0(0), 1);
EXPECT_EQ(row0(1), 2);
EXPECT_EQ(row1(0), 3);
EXPECT_EQ(row1(1), 4);
}

TEST(xiew, row_on_2dim_xtensor)
{
xt::xtensor<int, 2> tensor{
{ 1, 2 },
{ 3, 4 },
};

std::cout << tensor.shape().size() << std::endl;

const auto row0 = xt::row(tensor, 0);
const auto row1 = xt::row(tensor, 1);

EXPECT_EQ(row0(0), 1);
EXPECT_EQ(row0(1), 2);
EXPECT_EQ(row1(0), 3);
EXPECT_EQ(row1(1), 4);
}

TEST(xiew, row_on_2dim_xtensor_fixed)
{
xt::xtensor_fixed<int, xshape<2, 2>> tensor_fixed{
{ 1, 2 },
{ 3, 4 },
};

const auto row0 = xt::row(tensor_fixed, 0);
const auto row1 = xt::row(tensor_fixed, 1);

EXPECT_EQ(row0(0), 1);
EXPECT_EQ(row0(1), 2);
EXPECT_EQ(row1(0), 3);
EXPECT_EQ(row1(1), 4);
}

TEST(xview, row_on_3dim_array)
{
xt::xarray<int> arr{
{ { 1, 2 }, { 3, 4 } },
{ { 5, 6 }, { 7, 8 } },
};

XT_ASSERT_THROW(
const auto row = xt::row(arr, 0),
std::invalid_argument
);
}

TEST(xview, col_on_2dim_xarray)
{
xt::xarray<int> array{
{ 1, 2 },
{ 3, 4 },
};

const auto col0 = xt::col(array, 0);
const auto col1 = xt::col(array, 1);

EXPECT_EQ(col0(0), 1);
EXPECT_EQ(col0(1), 3);
EXPECT_EQ(col1(0), 2);
EXPECT_EQ(col1(1), 4);
}

TEST(xview, col_on_2dim_xtensor)
{
xt::xtensor<int, 2> tensor{
{ 1, 2 },
{ 3, 4 },
};

const auto col0 = xt::col(tensor, 0);
const auto col1 = xt::col(tensor, 1);

EXPECT_EQ(col0(0), 1);
EXPECT_EQ(col0(1), 3);
EXPECT_EQ(col1(0), 2);
EXPECT_EQ(col1(1), 4);
}

TEST(xview, col_on_2dim_xtensor_fixed)
{
xt::xtensor_fixed<int, xshape<2, 2>> tensor_fixed{
{ 1, 2 },
{ 3, 4 },
};

const auto col0 = xt::col(tensor_fixed, 0);
const auto col1 = xt::col(tensor_fixed, 1);

EXPECT_EQ(col0(0), 1);
EXPECT_EQ(col0(1), 3);
EXPECT_EQ(col1(0), 2);
EXPECT_EQ(col1(1), 4);
}

TEST(xview, col_on_3dim_array)
{
xt::xarray<int> arr{
{ { 1, 2 }, { 3, 4 } },
{ { 5, 6 }, { 7, 8 } },
};

XT_ASSERT_THROW(
const auto col = xt::col(arr, 0),
std::invalid_argument
);
}

// This code should not compile!
//TEST(xview, col_on_3dim_xtensor)
//{
// xt::xtensor<int, 3> tensor;
// xt::row(tensor, 0);
// xt::col(tensor, 0);
//}
}