RawRef in ndarray - Rust

RawRef in ndarray - Rust

pub struct RawRef<A, D>(/* private fields */);

Expand description

A reference to an n-dimensional array whose data is not safe to read or write.

This type is similar to ArrayRef but does not guarantee that its data is safe to read or write; i.e., the underlying data may come from a shared array or be otherwise unsafe to dereference. This type should be used sparingly and with extreme caution; most of its methods either provide pointers or return RawArrayView, both of which tend to be full of unsafety.

For the few times when this type is appropriate, it has the same AsRef semantics as LayoutRef; see its documentation on writing functions for information on how to properly handle functionality on this type.

Return a raw pointer to the element at index, or return None if the index is out of bounds.

use ndarray::arr2;

let a = arr2(&[[1., 2.], [3., 4.]]);

let v = a.raw_view();
let p = a.get_ptr((0, 1)).unwrap();

assert_eq!(unsafe { *p }, 2.);

Return a raw pointer to the element at index, or return None if the index is out of bounds.

use ndarray::arr2;

let mut a = arr2(&[[1., 2.], [3., 4.]]);

let v = a.raw_view_mut();
let p = a.get_mut_ptr((0, 1)).unwrap();

unsafe {
    *p = 5.;
}

assert_eq!(a.get((0, 1)), Some(&5.));

Return a pointer to the first element in the array.

Raw access to array elements needs to follow the strided indexing scheme: an element at multi-index I in an array with strides S is located at offset

Σ_{0 ≤ k < d} I_k × S_k

where d is self.ndim().

Return a mutable pointer to the first element in the array reference.

Return a raw view of the array.

Return a raw mutable view of the array.

Return the total number of elements in the array.

Return the length of axis.

The axis should be in the range Axis( 0 .. n ) where n is the number of dimensions (axes) of the array.

Panics if the axis is out of bounds.

Return whether the array has any elements

Return the number of dimensions (axes) in the array

Return the shape of the array in its “pattern” form, an integer in the one-dimensional case, tuple in the n-dimensional cases and so on.

Return the shape of the array as it’s stored in the array.

This is primarily useful for passing to other ArrayBase functions, such as when creating another array of the same shape and dimensionality.

use ndarray::Array;

let a = Array::from_elem((2, 3), 5.);

// Create an array of zeros that's the same shape and dimensionality as `a`.
let b = Array::<f64, _>::zeros(a.raw_dim());

Return the shape of the array as a slice.

Note that you probably don’t want to use this to create an array of the same shape as another array because creating an array with e.g. Array::zeros() using a shape of type &[usize] results in a dynamic-dimensional array. If you want to create an array that has the same shape and dimensionality as another array, use .raw_dim() instead:

use ndarray::{Array, Array2};

let a = Array2::<i32>::zeros((3, 4));
let shape = a.shape();
assert_eq!(shape, &[3, 4]);

// Since `a.shape()` returned `&[usize]`, we get an `ArrayD` instance:
let b = Array::zeros(shape);
assert_eq!(a.clone().into_dyn(), b);

// To get the same dimension type, use `.raw_dim()` instead:
let c = Array::zeros(a.raw_dim());
assert_eq!(a, c);

Return the strides of the array as a slice.

Return the stride of axis.

The axis should be in the range Axis( 0 .. n ) where n is the number of dimensions (axes) of the array.

Panics if the axis is out of bounds.

Slice the array in place without changing the number of dimensions.

In particular, if an axis is sliced with an index, the axis is collapsed, as in .collapse_axis(), rather than removed, as in .slice_move() or .index_axis_move().

See Slicing for full documentation. See also s!, SliceArg, and SliceInfo.

Panics in the following cases:

if an index is out of bounds
if a step size is zero
if SliceInfoElem::NewAxis is in info, e.g. if NewAxis was used in the s! macro
if D is IxDyn and info does not match the number of array axes

Slice the array in place along the specified axis.

Panics if an index is out of bounds or step size is zero.
Panics if axis is out of bounds.

Slice the array in place, with a closure specifying the slice for each axis.

This is especially useful for code which is generic over the dimensionality of the array.

Panics if an index is out of bounds or step size is zero.

Selects index along the axis, collapsing the axis into length one.

Panics if axis or index is out of bounds.

Return true if the array data is laid out in contiguous “C order” in memory (where the last index is the most rapidly varying).

Return false otherwise, i.e. the array is possibly not contiguous in memory, it has custom strides, etc.

Swap axes ax and bx.

This does not move any data, it just adjusts the array’s dimensions and strides.

Panics if the axes are out of bounds.

use ndarray::arr2;

let mut a = arr2(&[[1., 2., 3.]]);
a.swap_axes(0, 1);
assert!(
    a == arr2(&[[1.], [2.], [3.]])
);

Return an iterator over the length and stride of each axis.

Return the axis with the greatest stride (by absolute value), preferring axes with len > 1.

Reverse the stride of axis.

Panics if the axis is out of bounds.

If possible, merge in the axis take to into.

Returns true iff the axes are now merged.

This method merges the axes if movement along the two original axes (moving fastest along the into axis) can be equivalently represented as movement along one (merged) axis. Merging the axes preserves this order in the merged axis. If take and into are the same axis, then the axis is “merged” if its length is ≤ 1.

If the return value is true, then the following hold:

The new length of the into axis is the product of the original lengths of the two axes.
The new length of the take axis is 0 if the product of the original lengths of the two axes is 0, and 1 otherwise.

If the return value is false, then merging is not possible, and the original shape and strides have been preserved.

Note that the ordering constraint means that if it’s possible to merge take into into, it’s usually not possible to merge into into take, and vice versa.

use ndarray::Array3;
use ndarray::Axis;

let mut a = Array3::<f64>::zeros((2, 3, 4));
assert!(a.merge_axes(Axis(1), Axis(2)));
assert_eq!(a.shape(), &[2, 1, 12]);

Panics if an axis is out of bounds.

Return the number of rows (length of Axis(0)) in the two-dimensional array.

use ndarray::{array, Axis};

let array = array![[1., 2.],
                   [3., 4.],
                   [5., 6.]];
assert_eq!(array.nrows(), 3);

// equivalent ways of getting the dimensions
// get nrows, ncols by using dim:
let (m, n) = array.dim();
assert_eq!(m, array.nrows());
// get length of any particular axis with .len_of()
assert_eq!(m, array.len_of(Axis(0)));

Return the number of columns (length of Axis(1)) in the two-dimensional array.

use ndarray::{array, Axis};

let array = array![[1., 2.],
                   [3., 4.],
                   [5., 6.]];
assert_eq!(array.ncols(), 2);

// equivalent ways of getting the dimensions
// get nrows, ncols by using dim:
let (m, n) = array.dim();
assert_eq!(n, array.ncols());
// get length of any particular axis with .len_of()
assert_eq!(n, array.len_of(Axis(1)));

Return true if the array is square, false otherwise.

§Examples

Square:

use ndarray::array;
let array = array![[1., 2.], [3., 4.]];
assert!(array.is_square());

Not square:

use ndarray::array;
let array = array![[1., 2., 5.], [3., 4., 6.]];
assert!(!array.is_square());

Insert new array axis of length 1 at axis, modifying the shape and strides in-place.

Panics if the axis is out of bounds.

use ndarray::{Axis, arr2, arr3};

let mut a = arr2(&[[1, 2, 3], [4, 5, 6]]).into_dyn();
assert_eq!(a.shape(), &[2, 3]);

a.insert_axis_inplace(Axis(1));
assert_eq!(a, arr3(&[[[1, 2, 3]], [[4, 5, 6]]]).into_dyn());
assert_eq!(a.shape(), &[2, 1, 3]);

Collapses the array to index along the axis and removes the axis, modifying the shape and strides in-place.

Panics if axis or index is out of bounds.

use ndarray::{Axis, arr1, arr2};

let mut a = arr2(&[[1, 2, 3], [4, 5, 6]]).into_dyn();
assert_eq!(a.shape(), &[2, 3]);

a.index_axis_inplace(Axis(1), 1);
assert_eq!(a, arr1(&[2, 5]).into_dyn());
assert_eq!(a.shape(), &[2]);

Converts this type into a mutable reference of the (usually inferred) input type.

Converts this type into a mutable reference of the (usually inferred) input type.

Converts this type into a mutable reference of the (usually inferred) input type.

Converts this type into a mutable reference of the (usually inferred) input type.

Converts this type into a shared reference of the (usually inferred) input type.

Converts this type into a shared reference of the (usually inferred) input type.

Converts this type into a shared reference of the (usually inferred) input type.

Converts this type into a shared reference of the (usually inferred) input type.

The resulting type after dereferencing.

Dereferences the value.

Mutably dereferences the value.