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restaurant-search/server/search.js

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JavaScript
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'use strict';
var _ = require('underscore');
var mysql = require('mysql');
var connection = null;
function innerProduct(values1, values2) {
var result = 0.0;
for (var feature in values1) {
result += values1[feature] * (values2[feature] || 0.0);
}
return result;
}
function scale(values, factor) {
var result = {};
for (var feature in values) {
result[feature] = values[feature] * factor;
}
return result;
}
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function add(values1, values2) {
var result = {};
for (var feature in values1) {
result[feature] = values1[feature] + (values2[feature] || 0.0);
}
return result;
}
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function combine(dict, params) {
var result = {};
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for (var key in params) {
var values = scale(dict[key], params[key]);
result = add(values, result);
}
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for (var key in result) {
var value = result[key];
value = Math.min(1.0, Math.max(-1.0, value));
result[key] = value;
}
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return result;
}
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function walkRecords(data, searchParams, minScore, callback) {
var features = combine(data.keywords, searchParams);
for (var i = 0, count = data.records.length; i < count; ++i) {
var record = data.records[i];
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var score = innerProduct(features, record.rating);
if (score >= minScore) {
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callback(record, score);
}
}
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return features;
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}
function countRecords(data, searchParams, minScore) {
var count = 0;
walkRecords(data, searchParams, minScore, function(record, score) {
++count;
});
return count;
}
function findRecords(data, searchParams, minScore) {
var results = [];
walkRecords(data, searchParams, minScore, function(record, score) {
results.push({
name: record.name,
url: 'http://www.tripadvisor.com' + record.relativeUrl,
score: score
});
});
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, searchParams, minScore, keyword, range, steps) {
var testParams = _.clone(searchParams);
var results = [];
step(range, steps, function(position) {
testParams[keyword] = position;
results.push({
sample: position,
count: countRecords(data, testParams, minScore)
});
});
return results;
}
function buildHints(data, searchParams, minScore, keyword, range, steps) {
var projection = project(
data,
searchParams,
minScore,
keyword,
range,
steps
);
var hints = [];
_.each(projection, function(result) {
hints.push({
sample: result.sample,
count: result.count
});
});
return hints;
}
function loadDb(params) {
connection = mysql.createConnection(params);
}
function addKeyword(query, callback) {
getKeywords(function(keywords) {
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var keyword = query.keyword.toLowerCase();
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var features = combine(keywords, query.params);
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var values = [
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keyword,
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features.food || 0.0,
features.service || 0.0,
features.value || 0.0,
features.atmosphere || 0.0
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];
connection.query('INSERT INTO keywords VALUES(?, ?, ?, ?, ?)', values, function(err) {
callback({
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keyword: keyword,
success: err === null
});
});
});
}
function removeKeyword(query, callback) {
connection.query('DELETE FROM keywords WHERE name=? AND name NOT IN (SELECT name FROM presets)', [query.keyword], function(err, fields) {
callback({
keyword: query.keyword,
success: err === null && fields.affectedRows > 0
});
});
}
function getKeywords(callback) {
connection.query('SELECT * FROM keywords', function(err, rows) {
if (err) {
throw err;
}
var keywords = {};
for (var i = 0, count = rows.length; i < count; ++i) {
var row = rows[i];
keywords[row.name] = {
food: row.food,
service: row.service,
value: row.value,
atmosphere: row.atmosphere
};
}
callback(keywords);
});
}
function getRecords(callback) {
connection.query('SELECT * FROM reviews', function(err, rows) {
if (err) {
throw err;
}
var records = _.map(rows, function(row) {
return {
name: row.name,
relativeUrl: row.url,
rating: {
food: row.food,
service: row.service,
value: row.value,
atmosphere: row.atmosphere
}
};
});
callback(records);
});
}
function getData(callback) {
getKeywords(function(keywords) {
getRecords(function(records) {
callback({
keywords: keywords,
records: records
});
});
});
}
function execQuery(query, callback) {
getData(function(data) {
var searchResults = findRecords(
data,
query.searchParams,
query.minScore * _.keys(query.searchParams).length
);
var graphColumns = {};
for (var keyword in query.searchParams) {
var searchHints = buildHints(
data,
query.searchParams,
query.minScore * _.keys(query.searchParams).length,
keyword,
query.searchRange,
query.hintSteps
);
graphColumns[keyword] = {
value: query.searchParams[keyword],
hints: searchHints,
steps: query.hintSteps
}
}
callback({
columns: graphColumns,
items: searchResults.slice(0, query.maxResults),
count: searchResults.length
});
});
}
module.exports = {
'loadDb': loadDb,
'addKeyword': addKeyword,
'removeKeyword': removeKeyword,
'getKeywords': getKeywords,
'execQuery': execQuery
};