| <!DOCTYPE html> |
| <!-- |
| Copyright (c) 2015 The Chromium Authors. All rights reserved. |
| Use of this source code is governed by a BSD-style license that can be |
| found in the LICENSE file. |
| --> |
| |
| <link rel="import" href="/extras/rail/rail_interaction_record.html"> |
| |
| <script> |
| 'use strict'; |
| |
| tr.exportTo('tr.e.rail', function() { |
| function RAILScore(opt_irs) { |
| this.interactionRecords_ = []; |
| if (opt_irs) |
| this.interactionRecords_.push.apply(this.interactionRecords_, opt_irs); |
| }; |
| |
| RAILScore.prototype = { |
| get interactionRecords() { |
| return this.interactionRecords_; |
| }, |
| |
| get overallScore() { |
| // The design of this algorithm is discussed here: https://goo.gl/Cc0H1z |
| // TODO(benjhayden): Make doc public and remove below comment? |
| // Until the doc is made public, this is basically a weighted average, |
| // where the weights are tunable. The weights are recommended to be higher |
| // for lower scores, so that lower scores will bring down the overallScore |
| // more than higher scores bring it up. The optional fields provide an |
| // opportunity to customize the tunable parameters based on IR type, |
| // duration, etc. The continuity and monotonicity of the weighting |
| // function are also important characteristics. The weighting function is |
| // not composed of meaningful sub-expressions; it is a monolithic |
| // combination of the score and tunable parameters, and is open to |
| // reformulation. |
| // The weighting function is graphed here: https://goo.gl/1blsXW |
| if (!this.interactionRecords.length) |
| return undefined; |
| |
| var numerator = 0; |
| var denominator = 0; |
| this.interactionRecords.forEach(function(ir) { |
| var score = ir.railScore; |
| |
| var scale = ir.railScoreScale; |
| if (scale === undefined) |
| scale = 3; |
| |
| var power = ir.railScorePower; |
| if (power === undefined) |
| power = 0.3; |
| |
| var base = ir.railScoreBase; |
| if (base === undefined) |
| base = Math.exp(1); |
| |
| var weight = Math.pow(base, -scale * Math.pow(score, power)); |
| numerator += score * weight; |
| denominator += weight; |
| }); |
| return numerator / denominator; |
| } |
| }; |
| |
| RAILScore.fromModel = function(model) { |
| var rirs = model.interaction_records.filter(function(ir) { |
| return ir instanceof tr.e.rail.RAILInteractionRecord; |
| }); |
| if (rirs.length === 0) |
| return undefined; |
| return new RAILScore(rirs); |
| }; |
| |
| return { |
| RAILScore: RAILScore |
| }; |
| }); |
| </script> |