#array #data-structure #multidimensional #matrix #blas

ndarray

An n-dimensional array for general elements and for numerics. Lightweight array views and slicing; views support chunking and splitting.

78 releases

0.12.1 Nov 21, 2018
0.11.2 Mar 21, 2018
0.11.0 Dec 29, 2017
0.10.13 Nov 16, 2017
0.3.0-alpha.1 Dec 27, 2015

#11 in Data structures

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34,006 downloads per month
Used in 185 crates (147 directly)

MIT/Apache

500KB
9K SLoC

ndarray implements an n-dimensional container for general elements and for numerics.

In n-dimensional we include for example 1-dimensional rows or columns, 2-dimensional matrices, and higher dimensional arrays. If the array has n dimensions, then an element in the array is accessed by using that many indices. Each dimension is also called an axis.

Highlights

  • Generic n-dimensional array
  • Slicing, also with arbitrary step size, and negative indices to mean elements from the end of the axis.
  • Views and subviews of arrays; iterators that yield subviews.
  • Higher order operations and arithmetic are performant
  • Array views can be used to slice and mutate any [T] data using ArrayView::from and ArrayViewMut::from.
  • Zip for lock step function application across two or more arrays or other item producers (NdProducer trait).

lib.rs:

The ndarray crate provides an n-dimensional container for general elements and for numerics.

In n-dimensional we include for example 1-dimensional rows or columns, 2-dimensional matrices, and higher dimensional arrays. If the array has n dimensions, then an element in the array is accessed by using that many indices. Each dimension is also called an axis.

  • ArrayBase: The n-dimensional array type itself.
    It is used to implement both the owned arrays and the views; see its docs for an overview of all array features.
  • The main specific array type is Array, which owns its elements.

Highlights

  • Generic n-dimensional array
  • Slicing, also with arbitrary step size, and negative indices to mean elements from the end of the axis.
  • Views and subviews of arrays; iterators that yield subviews.
  • Higher order operations and arithmetic are performant
  • Array views can be used to slice and mutate any [T] data using ArrayView::from and ArrayViewMut::from.
  • Zip for lock step function application across two or more arrays or other item producers (NdProducer trait).

Crate Status

  • Still iterating on and evolving the crate
    • The crate is continuously developing, and breaking changes are expected during evolution from version to version. We adopt the newest stable rust features if we need them.
    • Note that functions/methods/traits/etc. hidden from the docs are not considered part of the public API, so changes to them are not considered breaking changes.
  • Performance:
    • Prefer higher order methods and arithmetic operations on arrays first, then iteration, and as a last priority using indexed algorithms.
    • The higher order functions like .map(), .map_inplace(), .zip_mut_with(), Zip and azip!() are the most efficient ways to perform single traversal and lock step traversal respectively.
    • Performance of an operation depends on the memory layout of the array or array view. Especially if it's a binary operation, which needs matching memory layout to be efficient (with some exceptions).
    • Efficient floating point matrix multiplication even for very large matrices; can optionally use BLAS to improve it further.
    • See also the ndarray-parallel crate for integration with rayon.
  • Requires Rust 1.27

Crate Feature Flags

The following crate feature flags are available. They are configured in your Cargo.toml.

  • rustc-serialize
    • Optional, compatible with Rust stable
    • Enables serialization support for rustc-serialize 0.3
  • serde-1
    • Optional, compatible with Rust stable
    • Enables serialization support for serde 1.0
  • blas
    • Optional and experimental, compatible with Rust stable
    • Enable transparent BLAS support for matrix multiplication. Uses blas-src for pluggable backend, which needs to be configured separately.

Documentation

  • The docs for ArrayBase provide an overview of the n-dimensional array type. Other good pages to look at are the documentation for the s![] and azip!() macros.

  • If you have experience with NumPy, you may also be interested in ndarray_for_numpy_users.

Dependencies

~520–710KB
~14K SLoC