speed-percentile

A JavaScript utility to compute percentile speed from speed histogram.

Install

npm install @mapbox/speed-percentile

Test

cd to speed-percentile folder then run

npm test

Use

v1.x

var o1 = percentile(P1, P2, P3)

Computes the p-th precentile speed from a sparse hash speed histogram.

Inputs:

| param | data type | description | |---|---|---| | P1 | associative array with integer keys | speed histogram hash {<speed>:<count>}| | P2 | number or array | one or more percentiles in decimal | | P3 | string | algorithm flag (optional): 'R4', 'R5' (default) |

Algorithms:

• R4 – R's sample quantile Type 4, but with linearly interpolated lower tail
• R5 – R's sample quantile Type 5, but with both tails linearly interpolated

Outputs:

| output | data type | description | |:--|:--|:--| | o1 | number or array | corresponding speed(s) sorted in descending order |

v2.x

v2.x only has R5 algorithm.

var PercentileInterpolator = require('@mapbox/speed-percentile');

var hist = {10: 2, 30: 3, 40: 4};
var pi = new PercentileInterpolator(hist);  

// find speed from percentile
var speed = pi.getSpeed(0.7);
var speeds = pi.getSpeed([0.1, 0.7]);  // irrespective of input order, output is always in descending order

// find percentile from speed
var p = pi.getPercentile(30);
var ps = pi.getPercentile([20, 30]);   // irrespective of input order, output is always in descending order