JS数据操作

Question

我有这样一个数据：（真实记录远不止这些）

year    type    quantity
2011    A       1000
2012    B       1000
2012    C       1000
2012    A       1000
2015    A       1000

JSON:

[{year:2011, type:A, quantity:1000},...]

我希望得到这样的结果：（我希望每年和每种类型都有记录）

year    type    quantity
2011    A       1000
2011    B       -
2011    C       -
2012    A       1000
2012    B       1000
2012    C       1000
2015    A       1000
2015    B       -
2015    C       -

请问有什么好的方法吗？也欢迎下划线解决方案！

Answer 1

希望这能与下划线一起使用：

var source = [{year: "2011", type: "A",...} ...];
var years = _.uniq(_.map(source , function(item){
    return item.year;
}))

var types = _.uniq(_.map(source , function(item){
    return item.type;
}))

var result = [];
_.each(years, function(yearItem){
    _.each(types, function(typeItem){
      var resultItem = _.find(source, function(item){
            return item.year === yearItem && item.type === typeItem;
        })
       if(undefined === resultItem){
             resultItem = {
               year: yearItem,
               type: typeItem,
               quantity: "-"
             };{}
       } 
           result.push(resultItem);


    })
})

Answer 2

带有jquery

的稍微优化的版本

var source = [{year:2011, type: 'A', quantity:100},{year:2012, type: 'B', quantity:200}],
    product = [],
    types = {}, 
    years = {}, 
    quantities = {};

$.each(source, function(i){
    var type = source[i].type, 
        year = source[i].year;
    types[type]= true;
    years[year]= true;
    if (typeof quantities[type] == "undefined")
        quantities[type] = {};
    quantities[type][year] = source[i].quantity;
});

$.each(types, function(type){
    var qts = quantities[type];
    $.each(years, function(year){
        var value = "-";
        if (typeof qts[year] != "undefined")
            value = qts[year];
        product.push({year:year, type: type, quantity:value});
    });
});

console.log(product);

通过在一个循环中提取类型和年份来节省时间，并且不存储重复值（因此不需要 .unique）。

JSFiddle demo

Answer 3

Vanilla JS，包括最终排序

var yrs = [], types = [], tmp={};

data.forEach(function(item){
     // create arrays of years and types
     if(yrs.indexOf(item.yr) === -1){
        yrs.push(item.yr);
    }
    if(types.indexOf(item.type) === -1){
        types.push(item.type);
    }
    // temp object used in next step to look for holes
    tmp[item.yr + item.type] = true;
});

yrs.forEach(function(yr){
    types.forEach(function(type){
        // fill in holes
        if(!tmp.hasOwnProperty(yr+type)){
           data.push({yr: yr, type: type, qty: 0});
         }
    })
});

data.sort(function(a,b){
    return b.yr === a.yr ? a.type > b.type : +a.yr - +b.yr
});

DEMO

JS数据操作

JS data manipulation

javascript

jquery

json

underscore.js