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restaurant-search/server/search.js

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JavaScript
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#!/usr/bin/env node
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/*
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* Copyright (c) 2015 Alex Yatskov <alex@foosoft.net>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
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'use strict';
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var _ = require('underscore');
var geolib = require('geolib');
var mysql = require('mysql');
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var uuid = require('node-uuid');
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var pool = null;
function innerProduct(values1, values2) {
var result = 0.0;
for (var feature in values1) {
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if (feature in values2) {
result += values1[feature] * values2[feature];
}
}
return result;
}
function walkMatches(data, features, minScore, callback) {
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for (var i = 0, count = data.length; i < count; ++i) {
var record = data[i];
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var score = innerProduct(features, record.features);
if (score >= minScore) {
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callback(record, score);
}
}
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}
function countRecords(data, features, minScore) {
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var count = 0;
walkMatches(data, features, minScore, function(record, score) {
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++count;
});
return count;
}
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function findRecords(data, features, minScore) {
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var results = [];
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walkMatches(data, features, minScore, function(record, score) {
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results.push({
name: record.name,
url: 'http://www.tripadvisor.com' + record.relativeUrl,
score: score,
distanceToUser: record.distanceToUser / 1000.0,
distanceToStn: record.distanceToStn / 1000.0,
closestStn: record.closestStn,
id: record.id
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});
});
results.sort(function(a, b) {
return b.score - a.score;
});
return results;
}
function step(range, steps, callback) {
var stepSize = (range.max - range.min) / steps;
for (var i = 0; i < steps; ++i) {
var stepMax = range.max - stepSize * i;
var stepMin = stepMax - stepSize;
var stepMid = (stepMin + stepMax) / 2;
callback(stepMid);
}
}
function project(data, features, feature, minScore, range, steps) {
var sample = _.clone(features);
var results = [];
step(range, steps, function(position) {
sample[feature] = position;
results.push({
sample: position,
count: countRecords(data, sample, minScore)
});
});
return results;
}
function buildHints(data, features, feature, minScore, range, steps) {
var projection = project(
data,
features,
feature,
minScore,
range,
steps
);
var hints = [];
_.each(projection, function(result) {
hints.push({
sample: result.sample,
count: result.count
});
});
return hints;
}
function loadDb(params) {
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pool = mysql.createPool(params);
}
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function getRecords(context, callback) {
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pool.query('SELECT * FROM reviews', function(err, rows) {
if (err) {
throw err;
}
var records = _.map(rows, function(row) {
return {
name: row.name,
id: row.id,
relativeUrl: row.url,
closestStn: row.closestStn,
distanceToStn: row.distanceToStn,
geo: {
latitude: row.latitude,
longitude: row.longitude
},
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features: {
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delicious: row.delicious,
accomodating: row.accomodating,
affordable: row.affordable,
atmospheric: row.atmospheric
},
};
});
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computeRecordGeo(records, context);
callback(records);
});
}
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function computeRecordGeo(records, context) {
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var distUserMin = Number.MAX_VALUE;
var distUserMax = Number.MIN_VALUE;
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_.each(records, function(record) {
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record.distanceToUser = 0.0;
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if (context.geo) {
record.distanceToUser = geolib.getDistance(record.geo, context.geo);
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}
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distUserMin = Math.min(distUserMin, record.distanceToUser);
distUserMax = Math.max(distUserMax, record.distanceToUser);
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});
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var distUserRange = distUserMax - distUserMin;
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_.each(records, function(record) {
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record.features.nearby = -((record.distanceToUser - distUserMin) / distUserRange - 0.5) * 2.0;
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record.features.accessible = 1.0 - (record.distanceToStn / context.walkingDist);
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record.features.accessible = Math.min(record.features.accessible, 1.0);
record.features.accessible = Math.max(record.features.accessible, -1.0);
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});
}
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function sanitizeQuery(query) {
var keys = [
'delicious',
'accomodating',
'affordable',
'atmospheric',
'nearby',
'accessible'
];
var features = {};
_.each(keys, function(key) {
features[key] = _.has(query.features, key) ? query.features[key] : 0.0;
});
query.features = features;
}
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function getCategories(callback) {
pool.query('SELECT * FROM categories', function(err, rows) {
if (err) {
throw err;
}
var categories = _.map(rows, function(row) {
return {id: row.id, description: row.description};
});
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callback(categories.reverse());
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});
}
function addCategory(query, callback) {
var description = query.description.trim();
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var id = uuid.v1();
if (description) {
pool.query('INSERT INTO categories(description, id) VALUES(?, ?)', [description, id], function(err, rows) {
if (err) {
throw err;
}
callback({
id: id,
description: description,
success: true
});
});
}
else {
callback({success: false});
}
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}
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function runQuery(query, callback) {
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sanitizeQuery(query);
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var context = {
geo: query.geo,
walkingDist: query.walkingDist * 1000.0
};
getRecords(context, function(data) {
var searchResults = findRecords(
data,
query.features,
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query.minScore
);
var graphColumns = {};
for (var feature in query.features) {
var searchHints = buildHints(
data,
query.features,
feature,
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query.minScore,
query.range,
query.hintSteps
);
graphColumns[feature] = {
value: query.features[feature],
hints: searchHints,
steps: query.hintSteps
};
}
callback({
columns: graphColumns,
items: searchResults.slice(0, query.maxResults),
count: searchResults.length
});
});
}
module.exports = {
loadDb: loadDb,
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runQuery: runQuery,
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getCategories: getCategories,
addCategory: addCategory
};