Macro ndarray::s [−] [src]

macro_rules! s {
    (@parse $dim:expr, [$($stack:tt)*] $r:expr;$s:expr) => { ... };
    (@parse $dim:expr, [$($stack:tt)*] $r:expr) => { ... };
    (@parse $dim:expr, [$($stack:tt)*] $r:expr;$s:expr ,) => { ... };
    (@parse $dim:expr, [$($stack:tt)*] $r:expr ,) => { ... };
    (@parse $dim:expr, [$($stack:tt)*] $r:expr;$s:expr, $($t:tt)*) => { ... };
    (@parse $dim:expr, [$($stack:tt)*] $r:expr, $($t:tt)*) => { ... };
    (@convert $r:expr) => { ... };
    (@convert $r:expr, $s:expr) => { ... };
    ($($t:tt)*) => { ... };
}

Slice argument constructor.

s![] takes a list of ranges/slices/indices, separated by comma, with optional step sizes that are separated from the range by a semicolon. It is converted into a &SliceInfo instance.

Each range/slice/index uses signed indices, where a negative value is counted from the end of the axis. Step sizes are also signed and may be negative, but must not be zero.

The syntax is s![ [ axis-slice-or-index [, axis-slice-or-index [ , ... ] ] ] ], where axis-slice-or-index is any of the following:

  • index: an index to use for taking a subview with respect to that axis
  • range: a range with step size 1 to use for slicing that axis
  • range ; step: a range with step size step to use for slicing that axis
  • slice: a Slice instance to use for slicing that axis
  • slice ; step: a range constructed from the start and end of a Slice instance, with new step size step, to use for slicing that axis

The number of axis-slice-or-index must match the number of axes in the array. index, range, slice, and step can be expressions. index must be of type isize, usize, or i32. range must be of type Range<I>, RangeTo<I>, RangeFrom<I>, or RangeFull where I is isize, usize, or i32. step must be a type that can be converted to isize with the as keyword.

For example s![0..4;2, 6, 1..5] is a slice of the first axis for 0..4 with step size 2, a subview of the second axis at index 6, and a slice of the third axis for 1..5 with default step size 1. The input array must have 3 dimensions. The resulting slice would have shape [2, 4] for .slice(), .slice_mut(), and .slice_move(), and shape [2, 1, 4] for .slice_inplace().

See also Slicing.

Example

#[macro_use]
extern crate ndarray;

use ndarray::{Array2, ArrayView2};

fn laplacian(v: &ArrayView2<f32>) -> Array2<f32> {
    -4. * &v.slice(s![1..-1, 1..-1])
    + v.slice(s![ ..-2, 1..-1])
    + v.slice(s![1..-1,  ..-2])
    + v.slice(s![1..-1, 2..  ])
    + v.slice(s![2..  , 1..-1])
}