在每个组中查找排名前N位的数据,其中N作为参数提供。等级和组的名称也作为参数提供。
鉴于以下数据:[ {姓名:'Tyler Bennett',id:'E10297',薪水:32000,部门:'D101'}, {姓名:'John Rappl',id:'E21437',薪水:47000,部门:'D050'}, {姓名:'George Woltman',id:'E00127',薪水:53500,部门:'D101'}, {name:'Adam Smith',id:'E63535',薪水:18000,部门:'D202'}, {姓名:'Claire Buckman',id:'E39876',薪水:27800,部门:'D202'}, {姓名:'David McClellan',id:'E04242',薪水:41500,部门:'D101'}, {name:'Rich Holcomb',id:'E01234',薪水:49500,dept:'D202'}, {姓名:'Nathan Adams',id:'E41298',薪水:21900,部门:'D050'}, {姓名:'Richard Potter',id:'E43128',薪水:15900,部门:'D101'}, {姓名:'David Motsinger',id:'E27002',薪水:19250,dept:'D202'}, {姓名:'Tim Sampair',id:'E03033',薪水:27000,部门:'D101'}, {姓名:'Kim Arlich',id:'E10001',薪水:57000,部门:'D190'}, {name:'Timothy Grove',id:'E16398',薪水:29900,部门:'D190'} ]。通过调用
topRankPerGroup(10, data, 'dept', 'salary')
可以对每个部门的前10名员工进行排名。给出以下数据: [ {name:'Friday 13th',类型:'恐怖',评分:9.9}, {姓名:“榆树街上的梦魇”,类型:'恐怖',等级:5.7}, {name:'Titanic',类型:'drama',评分:7.3}, {name:'Maze Runner',类型:'scifi',评级:7.1}, {name:'Blade runner',类型:'scifi',评分:8.9} ]。通过调用
topRankPerGroup(1, data, 'genre', 'rating')
可以在每个类型中对排名最高的电影进行排名topRankPerGroup
是一个函数。
testString: 'assert(typeof topRankPerGroup === "function", "topRankPerGroup
is a function.");'
- text: topRankPerGroup
在负n值上返回undefined。
testString: 'assert(typeof topRankPerGroup(-1, []) === "undefined", "topRankPerGroup
returns undefined on negative n values.");'
- text: 第一部门必须是D050
testString: 'assert.equal(res1[0][0].dept, "D050", "First department must be D050");'
- text: 第一部门必须是D050
testString: 'assert.equal(res1[0][1].salary, 21900, "First department must be D050");'
- text: 最后一个部门必须是D202
testString: 'assert.equal(res1[3][3].dept, "D202", "The last department must be D202");'
- text: 'topRankPerGroup(1, ...)
必须仅返回每组的排名最高的结果。'
testString: 'assert.equal(res2[2].length, 1, "topRankPerGroup(1, ...)
must return only top ranking result per group.");'
- text: 'topRankPerGroup(1, ...)
必须仅返回每组的排名最高的结果。'
testString: 'assert.equal(res3[2][1].name, "Maze Runner", "topRankPerGroup(1, ...)
must return only top ranking result per group.");'
```