layout¶
Defined in xtensor/xlayout.hpp
-
enum
xt
::
layout_type
¶ layout_type enum for xcontainer based xexpressions
Values:
-
dynamic
= 0x00¶ dynamic layout_type: you can resize to row major, column major, or use custom strides
-
any
= 0xFF¶ layout_type compatible with all others
-
row_major
= 0x01¶ row major layout_type
-
column_major
= 0x02¶ column major layout_type
-
-
template<class ...
Args
>
constexpr layout_typext
::
compute_layout
(Args... args)¶ Implementation of the following logical table:
Using bitmasks to avoid nested if-else statements.| d | a | r | c | --+---+---+---+---+ d | d | d | d | d | a | d | a | r | c | r | d | r | r | d | c | d | c | d | c | d = dynamic, a = any, r = row_major, c = column_major.
- Return
the output layout, computed with the previous logical table.
- Parameters
args
: the input layouts.
xcontainer¶
Defined in xtensor/xcontainer.hpp
-
template<class
D
>
classxcontainer
: public xt::xcontiguous_iterable<D>, private xt::xaccessible<D>¶ Base class for dense multidimensional containers.
The xcontainer class defines the interface for dense multidimensional container classes. It does not embed any data container, this responsibility is delegated to the inheriting classes.
- Template Parameters
D
: The derived type, i.e. the inheriting class for which xcontainer provides the interface.
Subclassed by xt::xstrided_container< D >
Size and shape
-
auto
size
() const¶ Returns the number of element in the container.
-
constexpr auto
dimension
() const¶ Returns the number of dimensions of the container.
-
constexpr auto
shape
() const¶ Returns the shape of the container.
-
constexpr auto
strides
() const¶ Returns the strides of the container.
-
constexpr auto
backstrides
() const¶ Returns the backstrides of the container.
Data
-
template<class
T
>
voidfill
(const T &value)¶ Fills the container with the given value.
- Parameters
value
: the value to fill the container with.
-
auto
storage
()¶ Returns a reference to the buffer containing the elements of the container.
-
auto
storage
() const¶ Returns a constant reference to the buffer containing the elements of the container.
-
auto
data
()¶ Returns a pointer to the underlying array serving as element storage.
The pointer is such that range [data(); data() + size()] is always a valid range, even if the container is empty (data() is not is not dereferenceable in that case)
-
auto
data
() const¶ Returns a constant pointer to the underlying array serving as element storage.
The pointer is such that range [data(); data() + size()] is always a valid range, even if the container is empty (data() is not is not dereferenceable in that case)
-
auto
data_offset
() const¶ Returns the offset to the first element in the container.
-
template<class ...
Args
>
autooperator()
(Args... args)¶ Returns a reference to the element at the specified position in the container.
- Parameters
args
: a list of indices specifying the position in the container. Indices must be unsigned integers, the number of indices should be equal or greater than the number of dimensions of the container.
-
template<class ...
Args
>
autooperator()
(Args... args) const¶ Returns a constant reference to the element at the specified position in the container.
- Parameters
args
: a list of indices specifying the position in the container. Indices must be unsigned integers, the number of indices should be equal or greater than the number of dimensions of the container.
-
template<class ...
Args
>
autounchecked
(Args... args)¶ Returns a reference to the element at the specified position in the container.
- Warning
This method is meant for performance, for expressions with a dynamic number of dimensions (i.e. not known at compile time). Since it may have undefined behavior (see parameters), operator() should be prefered whenever it is possible.
- Warning
This method is NOT compatible with broadcasting, meaning the following code has undefined behavior:
xt::xarray<double> a = {{0, 1}, {2, 3}}; xt::xarray<double> b = {0, 1}; auto fd = a + b; double res = fd.uncheked(0, 1);
- Parameters
args
: a list of indices specifying the position in the container. Indices must be unsigned integers, the number of indices must be equal to the number of dimensions of the container, else the behavior is undefined.
-
template<class ...
Args
>
autounchecked
(Args... args) const¶ Returns a constant reference to the element at the specified position in the container.
- Warning
This method is meant for performance, for expressions with a dynamic number of dimensions (i.e. not known at compile time). Since it may have undefined behavior (see parameters), operator() should be prefered whenever it is possible.
- Warning
This method is NOT compatible with broadcasting, meaning the following code has undefined behavior:
xt::xarray<double> a = {{0, 1}, {2, 3}}; xt::xarray<double> b = {0, 1}; auto fd = a + b; double res = fd.uncheked(0, 1);
- Parameters
args
: a list of indices specifying the position in the container. Indices must be unsigned integers, the number of indices must be equal to the number of dimensions of the container, else the behavior is undefined.
-
template<class
It
>
autoelement
(It first, It last)¶ Returns a reference to the element at the specified position in the container.
- Parameters
first
: iterator starting the sequence of indiceslast
: iterator ending the sequence of indices The number of indices in the sequence should be equal to or greater than the number of dimensions of the container.
-
template<class
It
>
autoelement
(It first, It last) const¶ Returns a reference to the element at the specified position in the container.
- Parameters
first
: iterator starting the sequence of indiceslast
: iterator ending the sequence of indices The number of indices in the sequence should be equal to or greater than the number of dimensions of the container.
Broadcasting
xstrided_container¶
Defined in xtensor/xcontainer.hpp
-
template<class
D
>
classxstrided_container
: public xt::xcontainer<D>¶ Partial implementation of xcontainer that embeds the strides and the shape.
The xstrided_container class is a partial implementation of the xcontainer interface that embed the strides and the shape of the multidimensional container. It does not embed the data container, this responsibility is delegated to the inheriting classes.
- Template Parameters
D
: The derived type, i.e. the inheriting class for which xstrided_container provides the partial imlpementation of xcontainer.
Public Functions
-
template<class
S
= shape_type>
voidresize
(S &&shape, bool force = false)¶ Resizes the container.
- Warning
Contrary to STL containers like std::vector, resize does NOT preserve the container elements.
- Parameters
shape
: the new shapeforce
: force reshaping, even if the shape stays the same (default: false)
-
template<class
S
= shape_type>
voidresize
(S &&shape, layout_type l)¶ Resizes the container.
- Warning
Contrary to STL containers like std::vector, resize does NOT preserve the container elements.
- Parameters
shape
: the new shapel
: the new layout_type
-
template<class
S
= shape_type>
voidresize
(S &&shape, const strides_type &strides)¶ Resizes the container.
- Warning
Contrary to STL containers like std::vector, resize does NOT preserve the container elements.
- Parameters
shape
: the new shapestrides
: the new strides
-
layout_type
layout
() const¶ Return the layout_type of the container.
- Return
layout_type of the container
-
template<class
S
>
auto &reshape
(S &&shape, layout_type layout) &¶ Reshapes the container and keeps old elements.
The
shape
argument can have one of its value equal to-1
, in this case the value is inferred from the number of elements in the container and the remaining values in theshape
.xt::xarray<int> a = { 1, 2, 3, 4, 5, 6, 7, 8 }; a.reshape({-1, 4}); //a.shape() is {2, 4}
- Parameters
shape
: the new shape (has to have same number of elements as the original container)layout
: the layout to compute the strides (defaults to static layout of the container, or for a container with dynamic layout to XTENSOR_DEFAULT_LAYOUT)