Question

求教！js二维数组中，如何把具有相同种类name的值筛选出来，组成三维数组

具体这样的，比如var college = [[{name:'北京'}, {city:'西安'}],
[{name:'上海'},{city:'包头'}],
[{name:'广州'},{city:'福州'}],
[{name:'北京'},{city:'广州'}],
[{name:'广州'},{city:'太原'}],
[{name:'上海'},{city:'昆明'}]];
要得到这种：
[[
[{name:'北京'}, {city:'西安'}],
[{name:'北京'}, {city:'广州'}]
],
[
[{name:'上海'},{city:'包头'}],
[{name:'上海'},{city:'昆明'}]
],
[
[{name:'广州'},{city:'福州'}],
[{name:'广州'},{city:'太原'}]
]];

Answer 1

var college = [
	[{name:'北京'}, {city:'西安'}],
	[{name:'上海'},{city:'包头'}],
	[{name:'广州'},{city:'福州'}],
	[{name:'北京'},{city:'广州'}],
	[{name:'广州'},{city:'太原'}],
	[{name:'上海'},{city:'昆明'}]
];

//先用map结构记录
function arrayToMap(data) {
	//非数组或数据长度为0不处理
	if(!data instanceof Array || data.length == 0) {
		return {};
	}
	var map = {};
	for(var i=0;i<data.length;i++) {
		if(!data[i] instanceof Array || data.length < 2) {
			continue;
		}
		
		var name = data[i][0].name;
		if(name != undefined) {
			 if(map[name] == undefined) {
				 map[name] = [];
			 }
			map[name].push(data[i]);
		}
	}
	return map;
}

//把map转成数组
function mapToArray(data) {
	if(data == undefined) {
		return [];
	}
	var array = [];
	for(p in data) {
		array.push(data[p]);
	}
	return array;
}

//测试
var map = arrayToMap(college);
var array = mapToArray(map);
console.log(array);

Answer 2

function merge(college) {
	var res = [],
		c = [];
	Array.prototype.forEach.call(college, function(item) {
		var i = c.indexOf(item[0].name);
		if (i < 0) {
			c.push(item[0].name);
			var a = [];
			a.push(item);
			res.push(a);
		} else {
			res[i].push(item);
		}
	});
	return res;
}

var res = merge(college);
res.forEach(function(row) {
	console.log(row);
})