nansum

Computes the sum of an array ignoring non-numeric values.

Installation

$ npm install compute-nansum

For use in the browser, use browserify.

Usage

var nansum = require( 'compute-nansum' );

nansum( arr[, accessor] )

Computes the sum of an array ignoring non-numeric values. For primitive arrays,

var data = [ 1, NaN, 2, NaN, 1 ];

var s = nansum( data );
// returns 4

For object arrays, provide an accessor function for accessing array values

var data = [
    {'x':1},
    {'x':NaN},
    {'x':2},
    {'x':NaN},
    {'x':1},
];

function getValue( d ) {
    return d.x;
}

var s = nansum( data, getValue );
// returns 4

Examples

var nansum = require( 'compute-nansum' );

var data = new Array( 1000 );
for ( var i = 0; i < data.length; i++ ) {
    if ( i%5 === 0 ) {
        data[ i ] = NaN;
    } else {
        data[ i ] = Math.random() * 100;
    }
}

console.log( nansum( data ) );

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

$ node ./examples/index.js

Notes

The sum of an array containing non-numeric values is equal to the sum of an equivalent array which contains only the numeric values. Hence,

var d1 = [ 1, NaN, 2, 3, NaN ],
    d2 = [ 1, 2, 3 ];

console.log( nansum( d1 ) === nansum( d2 ) );
// returns true

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.

Copyright

Copyright © 2014-2015. Athan Reines.