我正在使用JavaScript。我有一个包含这种格式数据的数组：
[ {USER_NAME：User1， LAST_SUCCESSFUL_CONNECT：1373978337642， {USER_NAME：User2，LAST_SUCCESSFUL_CONNECT：1374515704026}， {USER_NAME：User3，LAST_SUCCESSFUL_CONNECT：1374749782479 （上面的数字表示以毫秒为单位的UTC日期/时间。）我想按月对数据进行分组（计数），如下所示：我可以使用 jQuery 如果它简化了一些事情。 map reduce 问题。高级解决方案如下：
重新组织这个memb $ b 以下是一步一步的介绍如何实现这一点： Map
遍历字典列表 将datetime字符串转换为javascript datetime对象。 使用month-year作为键和词典列表作为值。 现在按月份分组。
例子：
var l = [...]; var o = {}; var f = function（x）{ var dt_object = Date（x [LAST_SUCCESSFUL_CONNECT]）; //转换为datetime对象 var key = dt_object.year +' - '+ dt_object.month; if（o [key] === undefined）{ var o [key] = []; }; $ b $ [b] bush（x）} _.map（l，f（x））//将f应用于l 减少
迭代包含列表字典的新对象。 计算每个字典列表的长度。 使用 count 作为键值和列表长度作为其值。 示例：
var g = function（member_count）{ //额外的逻辑可能会在这里返回member_count } 用于o { count = _.reduce（l，g（成员））成员['count'] = count } 结果API
o ['month-year'] //当月字典清单o ['month-year'] ['count'] //用于该月字典列表的计数。 参考文献：
在javascript中为 map 和 reduce 函数请参阅underscore.js： underscorejs/#map underscorejs/#reduce
Javascript日期对象： developer.mozilla/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date
有关Date和DateTime对象的更多信息： en.wikipedia/wiki/ISO_8601
有关 map 的更多信息， code> reduce ： https：/ /en.wikipedia/wiki/MapReduce
I'm using JavaScript. I have an array that contains data in this format:
[
{"USER_NAME":"User1","LAST_SUCCESSFUL_CONNECT":"1373978337642"},
{"USER_NAME":"User2","LAST_SUCCESSFUL_CONNECT":"1374515704026"},
{"USER_NAME":"User3","LAST_SUCCESSFUL_CONNECT":"1374749782479"}
]
(the numbers above represent UTC date/time in milliseconds.
I would like to group (count) the data by month. Something like this:
[
{"Month":"January, 2014","User_Count": 2},
{"Month":"February, 2014","User_Count": 1},
]
I could use jQuery if it simplifies matters.
解决方案 This looks like a map reduce problem. The high-level solution is as follows:
Re-organize the members of the list.
Count them.
Here is a step-by-step how-to for achieving this:
Map
Iterate through the list of dictionaries
Convert datetime string to javascript datetime object.
Use month-year as key and list of dictionaries as value.
These are now grouped by month-year.
Example:
var l = [...];
var o = {};
var f = function(x){
var dt_object = Date(x["LAST_SUCCESSFUL_CONNECT"]); // convert to datetime object
var key = dt_object.year + '-' + dt_object.month;
if (o[key] === undefined) {
var o[key] = [];
};
o[key].push(x)
}
_.map(l, f(x)) //apply f to each member of l
Reduce
Iterate through the new object containing dictionaries of lists.
Calculate length of each dictionary's list.
Use count as key and length of list as its value.
Example:
var g = function(member_count){
//extra logic may go here
return member_count
}
for member in o {
count = _.reduce(l, g(member))
member['count'] = count
}
Resulting API
o['month-year'] //for list of dictionaries in that month
o['month-year']['count'] //for the count of list of dictionaries in that month.
References:
For map and reduce functions in javascript see underscore.js:
underscorejs/#map
underscorejs/#reduce
Javascript Date object:
developer.mozilla/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date
For more information on Date and DateTime objects:
en.wikipedia/wiki/ISO_8601
For more information on map reduce:
en.wikipedia/wiki/MapReduce
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