mirror of https://github.com/pelias/api.git
Peter Johnson
6 years ago
committed by
Julian Simioni
10 changed files with 264 additions and 172 deletions
@ -1,51 +1,121 @@
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//example input
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//{
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// "source": {
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// "openstreetmap": 5
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// },
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// "layer": {
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// "street": 3,
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// "country": 5
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// }
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//}
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function generateTermQuery(field, value, boost) { |
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return { |
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constant_score: { |
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boost: boost, |
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query: { |
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term: { |
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[field]: value, |
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} |
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} |
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/** |
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This view allows users to specify a custom boost for sources and layers. |
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The view is implemented using a 'function_score' query, which enumerates multiple 'functions', each |
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function will assign a 'score' to each document when matched. |
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A document can match more than one function, in this case the 'score_mode' is used to decide how these |
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scores are combined, the default is 'sum'. |
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Likewise, a document can also match zero functions, in this case it is assigned a score of 'min_score'. |
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The computed score is then multiplied by the 'boost' value in order to come up with the final boost value |
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which will be assigned to that document. The 'boost' value is essentially a hard-coded multiplier for the score. |
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The 'max_boost' property is simply a ceiling for this computed boost, if the computed boosted is higher than |
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max_boost it will be assigned the value of max_boost instead. |
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Note: This is a simple use of the 'function_score' query, as such we don't use the 'boost_mode' property |
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(because there is no query section) and the 'weight' values we assign are simply returned verbatim |
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(because we use filter queries for the function scoring). |
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ref: https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-function-score-query.html
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example config section: |
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{ |
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"source": { |
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"openstreetmap": 5 |
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}, |
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"layer": { |
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"street": 3, |
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"country": 5 |
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} |
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}; |
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} |
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} |
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example query: |
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{ |
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"function_score": { |
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"query": { |
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"match_all": {} |
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}, |
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"functions": [{ |
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"filter": { |
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"match": { |
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"layer": "intersections" |
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} |
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}, |
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"weight": 1.6 |
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},{ |
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"filter": { |
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"match": { |
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"layer": "stops" |
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} |
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}, |
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"weight": 2.4 |
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}], |
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"boost": 5, |
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"max_boost": 40, |
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"score_mode": "sum", |
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"boost_mode": "multiply", |
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"min_score": 1 |
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} |
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} |
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**/ |
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// supported top-level config items
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const TARGETS = ['source', 'layer']; |
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module.exports = function( config ) { |
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module.exports = function( configuration ) { |
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return function( ) { |
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if (!configuration) { |
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// no valid config to use, fail now, don't render this view.
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if( !config ) { return function(){ return null; }; } |
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return function( vs ) { |
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// validate required params
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if( !vs.isset('custom:boosting:min_score') || |
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!vs.isset('custom:boosting:boost') || |
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!vs.isset('custom:boosting:max_boost') || |
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!vs.isset('custom:boosting:score_mode') || |
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!vs.isset('custom:boosting:boost_mode') ){ |
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return null; |
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} |
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const filters = []; |
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['source', 'layer'].forEach(function(target) { |
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if (configuration[target]) { |
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Object.keys(configuration[target]).forEach(function(item) { |
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filters.push(generateTermQuery(target, item, configuration[target][item])); |
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// base 'function_score' view
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var view = { |
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'function_score': { |
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'query': { 'match_all': {} }, // apply to all documents
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'functions': [], // a list of functions which contribute to a 'score' for each document
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'min_score': vs.var('custom:boosting:min_score'), |
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'boost': vs.var('custom:boosting:boost'), |
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'max_boost': vs.var('custom:boosting:max_boost'), |
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'score_mode': vs.var('custom:boosting:score_mode'), |
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'boost_mode': vs.var('custom:boosting:boost_mode') |
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}, |
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}; |
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// iterate over supported targets and their values
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TARGETS.forEach( function( target ) { |
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if( 'object' === typeof config[target] ) { |
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Object.keys(config[target]).forEach(function(value) { |
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// add a scoring function for this target, assigning a weight
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let weight = config[target][value]; |
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view.function_score.functions.push({ |
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'weight': isNaN(weight) ? 1 : weight, |
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'filter': { |
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'match': { |
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[target]: value |
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} |
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} |
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}); |
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}); |
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} |
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}); |
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if (filters.length === 0) { |
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return null; |
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} else if (filters.length === 1) { |
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return filters[0]; |
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} else { |
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return { |
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bool: { |
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should: filters |
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} |
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}; |
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} |
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// no functions were generated, fail now, don't render this view.
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if( view.function_score.functions.length === 0 ) { return null; } |
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return view; |
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}; |
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}; |
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