我想要一个函数
combineListOnKeys(listOfObjs, listOfKeys)
这将需要:
var listOfObjs =
[
{ name: john, state: ny, age: 12}
, { name: john, state: ny, age: 22}
, { name: john, state: dc, age: 32}
, { name: john, state: dc, age: 42}
, { name: paul, state: ca, age: 52}
]
var listOfKeys = ["name", "state"]
并返回:
combineListOnKeys(listOfObjs, listOfKeys)
[
{ "name": john, "state": ny, "age": [12, 22]}
,{ "name": john, "state": dc, "age": [32, 42]}
,{ "name": paul, "state": ca, "age": [52]}
]
我基本上是在寻找匹配所有这些对象共享的多个指定键,并获取剩余的未指定键并将它们组合到一个列表中,从而删除一些重复信息。
我正在使用 underscore.js,但我无法在文档中找到此问题的示例。提前致谢!
最佳答案
很抱歉,这不符合您修改后的功能要求,但我在您修改之前就开始了,并且付出了很多努力,我希望这足以让您组合出自己的功能。连续使用下划线的 _.reduce 和 _.each 方法(并且 _.each 可能会被第二个 _.reduce 或 _.map 替换——像往常一样,有不止一种方法可以做到这一点)。
var arr = [
{ name: 'john', state: 'ny', age: 12}
, { name: 'john', state: 'ny', age: 22}
, { name: 'john', state: 'dc', age: 32}
, { name: 'john', state: 'dc', age: 42}
, { name: 'paul', state: 'ca', age: 52}
];
var resultsMap = _.reduce(arr, function(memo, arrEl) {
/*
* var key = JSON.stringify(_.omit(arrEl, 'age'));
*
* From original answer but naively fails to account for Javascript objects not returning in order.
* See "IIFE" below and http://stackoverflow.com/a/28989092/34806
*/
var key = (function() {
var ageOmittedObj = _.omit(arrEl, 'age');
var ageOmittedPairs = _.pairs(ageOmittedObj);
var sortedPairs = _.reduce(_.keys(ageOmittedObj).sort(), function(sortedPairs, key) {
var pair = _.find(ageOmittedPairs, function(kvPair) {return kvPair[0] == key});
sortedPairs.push(pair);
return sortedPairs;
}, []);
return JSON.stringify(sortedPairs)
}) ();
memo[key] = memo[key] || {};
memo[key].ages = memo[key].ages || [];
memo[key].ages.push(arrEl.age);
return memo;
}, {});
var resultsArr = [];
_.each(resultsMap, function(v, k) {
var resultObj = {};
var nameStatePairs = JSON.parse(k);
var nameStateObj = _.object(_.map(nameStatePairs, function(pair){return [pair[0], pair[1]]}));
// compare above to http://stackoverflow.com/a/17802471/34806
resultObj.name = nameStateObj.name;
resultObj.state = nameStateObj.state;
resultObj.age = v.ages;
resultsArr.push(resultObj);
});
console.log(JSON.stringify(resultsArr));
// [{"name":"john","state":"ny","age":[12,22]},{"name":"john","state":"dc","age":[32,42]},{"name":"paul","state":"ca","age":[52]}]
关于javascript - 在键值对的唯一组合上合并对象,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/28973094/