I just pushed the latest version of psMathStats to GitHub. It had been sitting on the shelf 95% done for probably a year, but it is out at last. There are some new methods and while the syntax is almost exactly the same, it isn’t a drop-in replacement for 1.0 as it now uses my ps namespace.

New Features

A full breakdown of all the methods and functions of 2.0 are available on GitHub, but these are some of the new features.

• Array.sample
• Array.histogram
• Array.countByType
• Array.percentile
• ps.math.even
• ps.math.odd
• ps.math.product
• ps.math.randomBetween
• ps.math.randomNormal

Array.sample

Probably the biggest new feature is the ability to do sampling for any of the Array methods using Array.sample. It returns a randomly sampled array of any length less than or equal to the source array length. You can use it to quickly do calculations over large datasets (1MM+ rows) very quickly while sacrificing only a small amount of accuracy.

Here is an example:

// This will take a long time (many seconds) to run.
// Makes the browser become unresponsive
tenMillionRowArray.stdDev();

// Takes only a few milliseconds to run, and the
// returned value is almost exactly the same.
tenMillionRowArray.sample(20000).stdDev();

Suggestions

As always, if you have any other useful math or statistics functions you’d like to see implemented just drop me a line at Twitter or GitHub with some details on how to perform the calculation. Even better, just send me a pull-request with your implementation. ;)