spectrum-generator

spectrum-generator

Generates a spectrum from discrete peaks. The shape of the peaks can be customised.

In order to increase the speed a shape is first generated and then the peaks in the final spectrum are resulting from sampling the shape. A shape will therefore be generated with much more points (typically fwhm:1000).

The shape is generated using ml-peak-shape-generator and you may use all the corresponding options of getShape.

Installation

$ npm i spectrum-generator

Usage

The spectrum generator takes an array of discrete peaks (value and intensity) and generates peaks with a gaussian distribution (by default).

generateSpectrum

import { generateSpectrum } from 'spectrum-generator';

const peaks = [
  [4, 10],
  [20, 30],
  [236, 1],
  [569, 76],
];
const spectrum = generateSpectrum(peaks, {
  from: 0, // default value: 0
  to: 1000, // default value: 1000
  nbPoints: 10001, // default value: 10001
});

Example to generate a high resolution spectrum using lorentzian peaks shape

import { generateSpectrum } from 'spectrum-generator';

const peaks = [
  [1, 10],
  [2, 30],
  [3, 1],
  [4, 76],
];

/*
Peaks can also be introduced as:
- const peaks = [{x:1,y:10},{x:2,y:30},{x:3,y:1},{x:4,y:76}]
- const peaks = {x:[1,2,3,4], y:[10,30,1,76]}
*/

const spectrum = generateSpectrum(peaks, {
  nbPoints: 1001,
  from: 0,
  to: 10,
  shape: {
    kind: 'lorentzian',
    options: {
      fwhm: 1000,
      length: 10001,
    },
  },
});

class SpectrumGenerator

import { SpectrumGenerator } from 'spectrum-generator';

const generator = new SpectrumGenerator();
generator.addPeak([5, 20]);
generator.addPeak({ x: 5, y: 20 }); // we may either add an array of 2 elements or an object with x,y values
generator.addPeak([30, 56]);
generator.addPeaks([
  {x: 40, y: 12}, // it can also be an array of 2 elements
  {x: 10, y:1},
]);
const spectrum = generator.getSpectrum();

generator.reset();

generator.addPeak({x: 10, y: 50}], { // customize peaks shape
  width: 0.1, // width of peak is FWHM
  shape: {
    kind: 'lorentzian',
    options: {
      factor: 10, // 10 times fwhm. Lorentzian are rather flat
    },
  }
});

generator.addPeak({x: 10, y: 50, width: 2}) // specifiy the peak width. This is the peak width half height (FWHM)

generator.addPeak({x: 10, y: 50}], { // customize peaks shape
  width: 0.1,
  shape: {
    kind: 'gaussian',
    options: {
      fwhm: 1000,
      length: 10001,
    },
  }
});
const otherSpectrum = generator.getSpectrum();

API Documentation

License

MIT

Changelog

4.4.2 (2020-12-04)

Bug Fixes

• correct some shapes imperfections (eacf462)
• NaN bug (17a5fc9)