这是我的Map,Reduce和finalize功能。有4条匹配键的记录,当使用较少的数据(100s)调用mapreduce时结果正确,但是当使用更多数据(少量1000s)调用mapreduce时,常量计数为2。我检查了Reduce函数,对我来说它似乎是正确的,即使它在内部被多次调用以获得更大的数据。这变得很奇怪,我花了很长时间,仍然无法做到正确。
var map1 = function(){
var mapPosCnt = 0, mapPosSum = 0, mapZeroCnt = 0;
if (isNumber(this.val1)){
if(this.val1.toPrecision(10) > 0.0000000000){
mapPosCnt = 1;
mapPosSum = this.val1;
}else{
mapZeroCnt = 1;
}
}else{
mapPosCnt = 0, mapPosSum = 0, mapZeroCnt = 0;
}
emit({key1: this.key1, key2: this.key2+'', val1: 'val1'}
,{key1: this.key1, key2: this.key2+'', posCnt: mapPosCnt, posSum: mapPosSum, posAvg: 0, zeroCnt: mapZeroCnt, val1: this.val1});
}
var reduce1 = function(key, values){
var retval = {key1: key.CE, key2: key.key2, posCnt: 0, posSum: 0, posAvg: 0, zeroCnt: 0, val1: 0};
values.forEach(function(value){
if (isNumber(value.val1)){
if(value.val1.toPrecision(10) > 0.0000000000){
retval.posCnt += 1;
retval.posSum += value.val1;
}else{
retval.zeroCnt += 1;
}
}
})
return retval;
}
var finalize1 = function(key, value){
value.key2 = value.key2.toString();
if(value.posCnt > 0){
value.posSum = Math.round(value.posSum * Math.pow(10, 6)) / Math.pow(10, 6);
value.posAvg = Math.round((value.posSum/value.posCnt) * Math.pow(10, 6)) / Math.pow(10, 6);
}
return value;
}
collection1.mapReduce(map1, reduce1, {out: {merge: 'collection2'}, finalize: finalize1}, function(err, collection){});
答案 0 :(得分:1)
没有文档来测试它我猜了一下,但我可以看到几个问题:
{ posCnt: mapPosCnt, posSum: mapPosSum, zeroCnt: mapZeroCnt }
所以reduce1
应该是这样的:
var reduce1 = function(key, values){
var retval = { posCnt: 0, posSum: 0, zeroCnt: 0 };
values.forEach(function(value){
retval.posCnt += value.posCnt;
retval.posSum += value.posSum;
retval.zeroCnt += value.zeroCnt;
});
return retval;
};