logicle-js

This npm package provides some of the transformation functions of the package flowCore. The underlying cpp code is copied from flowCore with a slight modification, which will be described later, and exported to javascript through v8 and NAN.

Logicle is a transformation method which aims to give a better visualization of the data and is described in this paper and this paper. In short, the authors aim to provide a function which is an approximation of a linear function at around zero value and becomes logarithmic for larger values. They do so by forming a generalized version of the hyperbolic sine function: , whose the parameters a, b, c, d and f can be tuned for different datasets. The strategy for tuning the parameters is also described in the papers. Furthermore, instead of tuning those five parameters, the authors suggest using a more specific version of the function which involves four parameters, namely:

• T: The top of scale data value (e.g., 10,000 for common 4 decade data or 262,144 for an 18 bit data range).
• M: The breadth of the display in natural log units.
• W: The width of the range of linearized data in natural log units.
• A: The width of the negative data range in log units.

Those are the actual parameters that will be chosen by the user and passed to the functions of this package.

Installation

$ npm install logicle-trans

Usage

const api = require("logicle-trans");
// Available functions:
// LogicleTransform = function(x, T, M, W, A, inverse=false);
// FastLogicleTransform = function(x, T, M, W, A, inverse=false);
// HyperlogTransform = function(x, T, M, W, A, inverse=false);
api.LogicleTransform([3, 1.4, 7,2, 1000], 262144, 4.5, 0, 0);