simple-moving-avg

Calculate the simple moving average for an array.

Install

Install with npm:

$ npm install --save simple-moving-avg

Usage

var sma = require('simple-moving-avg');

API

sma

Calculate the simple moving average of a given array and using a subset of n elements. Note that elements that cannot be calculated because of not enough items in the subset will be set to 0

Example

var arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
console.log(sma(arr, 3));
//=> [ 0, 0, 2, 3, 4, 5, 6, 7, 8, 9 ]
 
// center the mean by passing `true` as the third argument
console.log(sma(arr, 3, true));
//=> [ 0, 2, 3, 4, 5, 6, 7, 8, 9, 0 ]

Params

• arr {Array}: Array containing full set of items to calcualte
• n {Number}: Number of items in each subset to use
• center {Boolean}: Center around the item in the array. Defaults to false. See center for more details.
• returns {Array}: Array containing averaged values

center

Calculate the simple moving average of a given array and using a subset of n elements. The subset is calculated around the current index using {i - ceil(n/2) .. i + ceil(n/2)}. This requires that n is odd to have a balanced number of items on either side of i. Note that elements that cannot be calculated because of not enough items in the subset will be set to 0

Example

console.log(sma.center(arr, 3));
//=> [ 0, 2, 3, 4, 5, 6, 7, 8, 9, 0 ]

Params

• arr {Array}: Array containing full set of items to calcualte
• n {Number}: Number of items in each subset to use
• returns {Array}: Array containing averaged values

calc

The calculation function used for calculating the next simple moving average in a series of simple moving averages. This is used in the sma and center functions after calculating the average of the first subset. This reduces the amount of times that the total array needs to be sliced and also allows for using the calculation function outside of this library when streaming an array of values.

Example

var prevAvg = avg([1, 2, 3]); // fake subset array with 3 values
var currentVal = 4; // current value (the value that would be next in the main array)
var firstVal = 1; // first value from the subset used to calculate the previous avg;
 
// create a calc function that will calculate the next average using a subset size of 3
var calcFn = sma.calc(3);
var currentAvg = calcFn(prevAvg, currentVal, firstVal);
console.log(currentAvg);
//=> 3

Params

• n {Number}: Size of the subsets
• precision {Number}: Number of decimal places to use. Defaults to 0
• returns {Number}: Average from the calculation.

About

Related projects

array-avg: Calculate the average of an array of numbers. | homepage

Contributing

Pull requests and stars are always welcome. For bugs and feature requests, please create an issue.

Please read the contributing guide for avice on opening issues, pull requests, and coding standards.

Building docs

(This document was generated by verb-generate-readme (a verb generator), please don't edit the readme directly. Any changes to the readme must be made in .verb.md.)

To generate the readme and API documentation with verb:

$ npm install -g verb verb-generate-readme && verb

Running tests

Install dev dependencies:

$ npm install -d && npm test

Author

Brian Woodward

• github/doowb
• twitter/doowb

License

Copyright © 2016, Brian Woodward. Released under the MIT license.

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This file was generated by verb-generate-readme, v0.2.0, on November 02, 2016.