我需要一个地图减少函数在mongo使用php
我需要一个地图减少函数在mongo使用php
提问于 2012-06-11 19:11:22
我需要一个由php的mongo地图减少功能
这是我的mongo结构
[_id] => MongoId Object (
[$id] => 4fcf2f2313cfcd2454500000d
)
[id] => 454
[table] => people
[news] => Array (
[03-06-2012] => 2
[04-06-2012] => 3
[05-06-2012] => 5
[06-06-2012] => 4
)在这里，我尝试用下面的代码对数组消息求和，
$map = new MongoCode('function() { emit(this.news, 1); }');
$reduce = new MongoCode('function(previous, current) {
var count = 0;
for (index in current) {
count = count + current[index];
}
return count;
}');
$sales = $db->command(array(
'mapreduce' => 'mycollection',
'map' => $map,
'reduce' => $reduce,
'query' => array('table' => 'people'),
'out' => 'news'
));
//pr($sales);exit;
$users = $db->selectCollection($sales['result'])->find();
foreach ($users as $user) {
//echo "{$user['_id']} had {$user['value']} sale(s).\n";
pr($user);
}当pr($user)
Array
(
[_id] => Array
(
[04-06-2012] => 0
[08-06-2012] => 2
[11-06-2012] => 6
)
[value] => 39540
)我期望的值将是8而不是39540。
如何纠正此函数，如何将字段sum作为'news‘的数组sum添加到原始集合(Mycollection)？
我不熟悉mongo中的map reduce函数。
Stack Overflow用户
发布于 2012-10-10 19:03:55
而jmikola的回答给了我处理mongo map reduce函数的wright track。
我添加这个答案是为了帮助未来的访问者。
下面的map-reduce函数完全符合我的要求。这会将新闻字段中的所有值相加到在command中通过添加("out" => "news")创建的名为news的新集合。
映射-Reduce函数
$map = new MongoCode('function() {
var total = 0;
for (count in this.news) {
total += this.news[count];
}
emit(this._id, {id: this.id, total: total});
}');
$reduce = new MongoCode('function(key, values) {
var result = {id: null, total: 0};
values.forEach(function(v) {
result.id = v.id;
result.total = v.total;
});
return result;
}');
$sales = $db->command(array(
'mapreduce' => 'mycollection', // collection name
'map' => $map,
'reduce' => $reduce,
'query' => array('table' => 'people'),
"out" => "news" // new collection name
));结果将是news集合，其中total为sum，实际文档为id
输出
[_id] => MongoId Object (
[$id] => 4fd8993a13cfcd4e42000000
)
[value] => Array (
[id] => 454
[total] => 14
)页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/10978975
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