doowb/sma

Calculate the simple moving average of an array.

sma

Calculate the simple moving average of an array.

Please consider following this project's author, Brian Woodward, and consider starring the project to show your ❤️ and support.

Install

Install with npm:

$ npm install --save sma

Usage

var sma = require('sma');

API

sma

Calculate the simple moving average of an array. A new array is returned with the average of each range of elements. A range will only be calculated when it contains enough elements to fill the range.

Params

• arr {Array}: Array of numbers to calculate.
• range {Number}: Size of the window to use to when calculating the average for each range. Defaults to array length.
• format {Function}: Custom format function called on each calculated average. Defaults to n.toFixed(2).
• returns {Array}: Resulting array of averages.

Example

console.log(sma([1, 2, 3, 4, 5, 6, 7, 8, 9], 4));
//=> [ '2.50', '3.50', '4.50', '5.50', '6.50', '7.50' ]
//=>   │       │       │       │       │       └─(6+7+8+9)/4
//=>   │       │       │       │       └─(5+6+7+8)/4
//=>   │       │       │       └─(4+5+6+7)/4
//=>   │       │       └─(3+4+5+6)/4
//=>   │       └─(2+3+4+5)/4
//=>   └─(1+2+3+4)/4

Attribution

Thanks to @jonschlinkert for simplifying the algorithm. For more moving average modules checkout the related projects below.

About

Contributing

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

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

Running Tests

Running and reviewing unit tests is a great way to get familiarized with a library and its API. You can install dependencies and run tests with the following command:

$ npm install && npm test

Building docs

(This project's readme.md is generated by verb, please don't edit the readme directly. Any changes to the readme must be made in the .verb.md readme template.)

To generate the readme, run the following command:

$ npm install -g verbose/verb#dev verb-generate-readme && verb

Related projects

You might also be interested in these projects:

exponential-moving-average: Calculate an exponential moving average from an array of numbers. | homepage

Author

Brian Woodward

• GitHub Profile
• Twitter Profile
• LinkedIn Profile

License

Copyright © 2018, Brian Woodward. Released under the MIT License.

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This file was generated by verb-generate-readme, v0.8.0, on September 12, 2018.

sma's Issues

Ability to pad the returned array with 'undefined' / lesser window sizes for values that can't be calculated

Is useful for my use case to ensure that the output array is the same size as the input array, even if the data is more odd.

topics

just a friendly reminder to add some topics to the lib to make it discoverable on github

Usage with decimals

I tried using this library with a decimal based array, and it returns ["0.00", "0.00", ....]

Is it intended to be used with decimals or can it be extended to?

code optimization suggestion

Hi there

https://github.com/doowb/sma/blob/master/index.js#L35

33:  var idx = num - 1;
34:  while (++idx < len) {
35:    res.push(fn(avg(arr, idx, idx < num ? idx : num)));
36:  }

Why do you check if idx is smaller than num (idx < num ? idx : num) on line 35 ??
idx can never be smaller than num because idx is num -1 and pre-incremented on line 34.
I guess that doesn't cause a problem but unnecessary.

Cheers