Question

我正在尝试使用map / reduce计算一年的频率，这是代码

map = %Q{
  function(){
    emit({}, { 
      year: this.birthdate.getFullYear(),
      count: 1
    })
  }
}
reduce = %Q{
  function(key, values){
    var agg = { }
    values.forEach( function(value){
      if(agg[value.year]){
        agg[value.year] += value.count
      } else {
        agg[key] = value.count
      }
    })
    return agg
  }
}
User.map_reduce(map, reduce).out(inline: true)

然后返回

=> [{"_id"=>{}, "value"=>{"2004"=>2.0, "2002"=>1.0, "2005"=>1.0}}]

但是我在我的数据库中有很多年，这只是追踪3。我怎么能这样做？

Answer 1

现在它的工作......这里是代码

map = %Q{
  function(){
    var today = new Date()
    var age = today.getFullYear() - this.birthdate.getFullYear()
    var m = today.getMonth() - this.birthdate.getMonth()
    if (m < 0 || (m === 0 && today.getDate() < this.birthdate.getDate()))
        age--

    emit(age, { count: 1 })
  }
}
reduce = %Q{
  function(key, values){
    var sum = 0

    values.forEach( function(value){
      sum += value.count
    })

    return { count: sum }
  }
}

scoped.map_reduce(map, reduce).out(inline: true)

计算一年的频率

1 个答案: