underscore.js - 使用 underdescore.js 过滤

Question

var data1 = [
    {"year":2000,"country":"Madagascar","country_id":847,"group":"Economic Statistics "},
    {"year":2005,"country":"Madagascar","country_id":847,"group":"Economic Statistics "},
    {"year":2000,"country":"Madagascar","country_id":847,"group":"Economic Statistics "},
    {"year":2005,"country":"Libya","country_id":846,"group":"Demographic  and Social Statistics "},
    {"year":2008,"country":"Libya","country_id":846,"group":"Demographic  and Social Statistics "},
    {"year":2005,"country":"Libya","country_id":846,"group":"Demographic  and Social Statistics "}
]

这是我的 JSON 数据，我想根据国家/地区和年份(唯一)使用 underscore.js 过滤它

Answer 1

如果要根据某个键选择唯一元素，可以使用 _.uniq (或 _.unique)方法。它可以选择使用回调将元素转换为其键进行比较。具有相同内容的数组比较为不同的，因此您可能需要对您的 ke 进行字符串化； JSON.stringify可以用于此(或者您可以使用 + - 有后果):

data1=_.uniq(data1, function(x){
    return JSON.stringify([x.year, x.country_id])
});

演示: http://jsfiddle.net/honnza/xGr9e/

如果您只想保留具有某些特定值的值 year和 country_id ，这更容易:

data1=_.filter(data1, function(x){
    return x.year === target_year && x.country_id === target_country_id
});