compute-euclidean-distance v1.0.0
Euclidean Distance
Computes the Euclidean distance between two arrays.
The Euclidean distance is the straight line distance between two points in Euclidean space.
Installation
$ npm install compute-euclidean-distance
For use in the browser, use browserify.
Usage
var euclidean = require( 'compute-euclidean-distance' );
euclidean( x, y, accessor )
Computes the Euclidean distance between two arrays.
var x = [ 2, 4, 5, 3, 8, 2 ],
y = [ 3, 1, 5, -3, 7, 2 ];
var d = euclidean( x, y );
// returns ~6.86
For object arrays
, provide an accessor function
for accessing numeric
values.
var x, y, d;
x = [
[1,2],
[2,4],
[3,5],
[4,3],
[5,8],
[6,2]
];
y = [
{'y':3},
{'y':1},
{'y':5},
{'y':-3},
{'y':7},
{'y':2}
];
function getValue( d, i, j ) {
if ( j === 0 ) {
return d[ 1 ];
}
return d.y;
}
d = euclidean( x, y, getValue );
// returns ~6.86
The accessor function
is provided three arguments:
- d: current datum.
- i: current datum index.
- j: array index; e.g., array
x
has index0
, and arrayy
has index1
.
If provided empty arrays
, the function returns null
.
Examples
var euclidean = require( 'compute-euclidean-distance' );
var x = new Array( 100 ),
y = new Array( 100 );
for ( var i = 0; i < x.length; i++ ) {
x[ i ] = Math.round( Math.random()*10 );
y[ i ] = Math.round( Math.random()*10 );
}
console.log( euclidean( x, y ) );
To run the example code from the top-level application directory,
$ node ./examples/index.js
References
Dahlquist, Germund and Bjorck, Ake. _Numerical Methods in Scientific Computing_.
Blue, James (1978) "A Portable Fortran Program To Find the Euclidean Norm of a Vector". _ACM Transactions on Mathematical Software_.
Higham, Nicholas J. _Accuracy and Stability of Numerical Algorithms, Second Edition_.
This module implements a one-pass algorithm proposed by S.J. Hammarling.
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
Copyright
Copyright © 2015. Athan Reines.