cast-arrays's Introduction

cast-arrays

Casts an array to an array of a different data type.

Installation

$ npm install dstructs-cast-arrays

For use in the browser, use browserify.

Usage

var cast = require( 'dstructs-cast-arrays' );

cast( x, type )

Casts an input array or array-like object to a specified array type.

var arr = Int32Array( 10 );

var out = cast( arr, 'float32' );
// returns Float32Array

type may be either a string specifying the desired output array data type or a value from which the desired data type should be inferred.

var x = Int32Array( 10 ),
	y = Float32Array( 25 );

// Cast `x` to be the same data type as `y`:
var out = cast( x, y );
// returns Float32Array

For a list of supported output array data types, see dstructs-array-constructors.

Examples

var cast = require( 'dstructs-cast-arrays' ),
	arr,
	x, y, z;

arr = new Int8Array( 10 );
x = cast( arr, 'int16' );
// returns Int16Array

arr = new Array( 100 );
y = cast( arr, 'float64' );
// returns Float64Array

z = cast( x, y );
// returns Float64Array

To run the example code from the top-level application directory,

$ node ./examples/index.js

Tests

Unit

Unit tests use the Mocha test framework with Chai assertions. To run the tests, execute the following command in the top-level application directory:

$ make test

All new feature development should have corresponding unit tests to validate correct functionality.

Test Coverage

This repository uses Istanbul as its code coverage tool. To generate a test coverage report, execute the following command in the top-level application directory:

$ make test-cov

Istanbul creates a ./reports/coverage directory. To access an HTML version of the report,

$ make view-cov

License

MIT license.

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Code Review

Small utility to cast an array from one data type to an array of a different data type. Effectively does a copy-by-value. Supports array-like objects, although best not to use to cast arguments to an array.

Relies on both compute-array-constructors and compute-array-dtypes being published before being publishable.

Move to dstructs?

Ensure fast elements

The current implementation assumes the input array is less than 64K when casting to a generic array. For arrays larger than 64K, the current implementation will return a sparse array. This should be remedied by using Array#push to ensure fast elements.