Eloquent_JavaScrip中的weresquirrel

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字数统计: 1,373 | 阅读时长 ≈ 8

看到了Eloquent_JavaScrip第四章（对象和数组）），这一章讲了一个松鼠人(weresquirrel)的故事，并用函数来找出其变身的原因，感觉很有趣，便动手实现了一下。数据连接

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var JOURNAL = [
  {"events":["carrot","exercise","weekend"],"squirrel":false},
  {"events":["bread","pudding","brushed teeth","weekend","touched tree"],"squirrel":false},
  {"events":["carrot","nachos","brushed teeth","cycling","weekend"],"squirrel":false},
  {"events":["brussel sprouts","ice cream","brushed teeth","computer","weekend"],"squirrel":false},
  {"events":["potatoes","candy","brushed teeth","exercise","weekend","dentist"],"squirrel":false},
  {"events":["brussel sprouts","pudding","brushed teeth","running","weekend"],"squirrel":false},
  {"events":["pizza","brushed teeth","computer","work","touched tree"],"squirrel":false},
  {"events":["bread","beer","brushed teeth","cycling","work"],"squirrel":false},
  {"events":["cauliflower","brushed teeth","work"],"squirrel":false},
  {"events":["pizza","brushed teeth","cycling","work"],"squirrel":false},
  {"events":["lasagna","nachos","brushed teeth","work"],"squirrel":false},
  {"events":["brushed teeth","weekend","touched tree"],"squirrel":false},
  {"events":["lettuce","brushed teeth","television","weekend"],"squirrel":false},
  {"events":["spaghetti","brushed teeth","work"],"squirrel":false},
  {"events":["brushed teeth","computer","work"],"squirrel":false},
  {"events":["lettuce","nachos","brushed teeth","work"],"squirrel":false},
  {"events":["carrot","brushed teeth","running","work"],"squirrel":false},
  {"events":["brushed teeth","work"],"squirrel":false},
  {"events":["cauliflower","reading","weekend"],"squirrel":false},
  {"events":["bread","brushed teeth","weekend"],"squirrel":false},
  {"events":["lasagna","brushed teeth","exercise","work"],"squirrel":false},
  {"events":["spaghetti","brushed teeth","reading","work"],"squirrel":false},
  {"events":["carrot","ice cream","brushed teeth","television","work"],"squirrel":false},
  {"events":["spaghetti","nachos","work"],"squirrel":false},
  {"events":["cauliflower","ice cream","brushed teeth","cycling","work"],"squirrel":false},
  {"events":["spaghetti","peanuts","computer","weekend"],"squirrel":true},
  {"events":["potatoes","ice cream","brushed teeth","computer","weekend"],"squirrel":false},
  {"events":["potatoes","ice cream","brushed teeth","work"],"squirrel":false},
  {"events":["peanuts","brushed teeth","running","work"],"squirrel":false},
  {"events":["potatoes","exercise","work"],"squirrel":false},
  {"events":["pizza","ice cream","computer","work"],"squirrel":false},
  {"events":["lasagna","ice cream","work"],"squirrel":false},
  {"events":["cauliflower","candy","reading","weekend"],"squirrel":false},
  {"events":["lasagna","nachos","brushed teeth","running","weekend"],"squirrel":false},
  {"events":["potatoes","brushed teeth","work"],"squirrel":false},
  {"events":["carrot","work"],"squirrel":false},
  {"events":["pizza","beer","work","dentist"],"squirrel":false},
  {"events":["lasagna","pudding","cycling","work"],"squirrel":false},
  {"events":["spaghetti","brushed teeth","reading","work"],"squirrel":false},
  {"events":["spaghetti","pudding","television","weekend"],"squirrel":false},
  {"events":["bread","brushed teeth","exercise","weekend"],"squirrel":false},
  {"events":["lasagna","peanuts","work"],"squirrel":true},
  {"events":["pizza","work"],"squirrel":false},
  {"events":["potatoes","exercise","work"],"squirrel":false},
  {"events":["brushed teeth","exercise","work"],"squirrel":false},
  {"events":["spaghetti","brushed teeth","television","work"],"squirrel":false},
  {"events":["pizza","cycling","weekend"],"squirrel":false},
  {"events":["carrot","brushed teeth","weekend"],"squirrel":false},
  {"events":["carrot","beer","brushed teeth","work"],"squirrel":false},
  {"events":["pizza","peanuts","candy","work"],"squirrel":true},
  {"events":["carrot","peanuts","brushed teeth","reading","work"],"squirrel":false},
  {"events":["potatoes","peanuts","brushed teeth","work"],"squirrel":false},
  {"events":["carrot","nachos","brushed teeth","exercise","work"],"squirrel":false},
  {"events":["pizza","peanuts","brushed teeth","television","weekend"],"squirrel":false},
  {"events":["lasagna","brushed teeth","cycling","weekend"],"squirrel":false},
  {"events":["cauliflower","peanuts","brushed teeth","computer","work","touched tree"],"squirrel":false},
  {"events":["lettuce","brushed teeth","television","work"],"squirrel":false},
  {"events":["potatoes","brushed teeth","computer","work"],"squirrel":false},
  {"events":["bread","candy","work"],"squirrel":false},
  {"events":["potatoes","nachos","work"],"squirrel":false},
  {"events":["carrot","pudding","brushed teeth","weekend"],"squirrel":false},
  {"events":["carrot","brushed teeth","exercise","weekend","touched tree"],"squirrel":false},
  {"events":["brussel sprouts","running","work"],"squirrel":false},
  {"events":["brushed teeth","work"],"squirrel":false},
  {"events":["lettuce","brushed teeth","running","work"],"squirrel":false},
  {"events":["candy","brushed teeth","work"],"squirrel":false},
  {"events":["brussel sprouts","brushed teeth","computer","work"],"squirrel":false},
  {"events":["bread","brushed teeth","weekend"],"squirrel":false},
  {"events":["cauliflower","brushed teeth","weekend"],"squirrel":false},
  {"events":["spaghetti","candy","television","work","touched tree"],"squirrel":false},
  {"events":["carrot","pudding","brushed teeth","work"],"squirrel":false},
  {"events":["lettuce","brushed teeth","work"],"squirrel":false},
  {"events":["carrot","ice cream","brushed teeth","cycling","work"],"squirrel":false},
  {"events":["pizza","brushed teeth","work"],"squirrel":false},
  {"events":["spaghetti","peanuts","exercise","weekend"],"squirrel":true},
  {"events":["bread","beer","computer","weekend","touched tree"],"squirrel":false},
  {"events":["brushed teeth","running","work"],"squirrel":false},
  {"events":["lettuce","peanuts","brushed teeth","work","touched tree"],"squirrel":false},
  {"events":["lasagna","brushed teeth","television","work"],"squirrel":false},
  {"events":["cauliflower","brushed teeth","running","work"],"squirrel":false},
  {"events":["carrot","brushed teeth","running","work"],"squirrel":false},
  {"events":["carrot","reading","weekend"],"squirrel":false},
  {"events":["carrot","peanuts","reading","weekend"],"squirrel":true},
  {"events":["potatoes","brushed teeth","running","work"],"squirrel":false},
  {"events":["lasagna","ice cream","work","touched tree"],"squirrel":false},
  {"events":["cauliflower","peanuts","brushed teeth","cycling","work"],"squirrel":false},
  {"events":["pizza","brushed teeth","running","work"],"squirrel":false},
  {"events":["lettuce","brushed teeth","work"],"squirrel":false},
  {"events":["bread","brushed teeth","television","weekend"],"squirrel":false},
  {"events":["cauliflower","peanuts","brushed teeth","weekend"],"squirrel":false}
];

/**
 * 判断是否有事件
 * @param {String}event 事件名称
 * @param {Object}entry   事件记录
 * @return {Boolean}      true是有 false是没有 
 */
var isEvent = function(event, entry) {
  //indexOf查找不到就返回-1，注意，在Bolean中false为0，所有非0 的都是true
  return entry.indexOf(event) !== -1
}

/**
 * 计算两件事件的相关性
 * @param {Number[]} record_tab ab 发生与否记作0和1，然后统计所有的情况记成数组
 * @return {string}}  二者的相关性[-1,1],使用了内置函数保留10为有效数字所以转化成了字符串
 */
var phi = function(record_tab) {
  let temp = Math.sqrt(
                      (record_tab[2] + record_tab[3]) * 
                      (record_tab[1] + record_tab[3]) * 
                      (record_tab[0] + record_tab[1]) * 
                      (record_tab[0] + record_tab[2]) )
  return ((record_tab[3] * record_tab[0] - record_tab[2] * record_tab[1]) /  temp).toFixed(10) 
}

/**
 * 统计事件与是否变身的相关性
 * @param {String} event 事件名称 
 * @param {Object} tab   事件记录
 * @return  {Number} 事件与变身的相关性[-1,1]
 */
var sth_pertinence = function(event, tab) {
  let phi_tab = [0,0,0,0]
  for(var i = 0; i < tab.length; i++) {
    let index = 0
    if(isEvent(event,tab[i].events)) {index++}
    if(tab[i].squirrel) {index += 2}
    phi_tab[index]++
  }
  return phi(phi_tab)
}

/**
 * 相关性映射表
 * @param {Object} tabs 记录表
 * @return {object} 相关性映射表
 */
var map_pertinence = function(tabs) {
  let map = {}
  for(let i = 0; i < tabs.length; i++) {
    for(let j = 0; j < tabs[i].events.length; j++){
      if( ! (tabs[i].events[j] in map)) {
        map[tabs[i].events[j]] = Number(sth_pertinence(tabs[i].events[j] ,JOURNAL)) 
      }
    }
  }
  return map
}


/**
 * 找出相关项
 * @param {object} map 相关性映射表
 * @return  {string} 分析结果
 */
var reous_pertinence = function(map) {
  let tab_phi = {}
  let reous = {
    max_tab : "",
    max_phi : -Infinity ,
    min_tab : "",
    min_phi : Infinity,
  }
  let end_resou = ""
  tab_phi = map_pertinence(JOURNAL)
  for(let event in tab_phi) { 
    if(tab_phi[event] <  reous.min_phi ) {
      reous.min_tab = event 
      reous.min_phi = tab_phi[event]
    } 
    if(tab_phi[event] > reous.max_phi) {
      reous.max_tab = event 
      reous.max_phi = tab_phi[event] 
    }
  }
 end_resou = reous.max_tab + "  no" + reous.min_tab
  for(let i = 0; i < JOURNAL.length ; i++){
    if(isEvent(reous.max_tab,JOURNAL[i].events) && !isEvent(reous.min_tab,JOURNAL[i].events) ){
      JOURNAL[i].events.push(end_resou)
    }
  }

  return end_resou +"  pshi:  "+ sth_pertinence(end_resou,JOURNAL)
}

console.log(reous_pertinence())

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