4.2 KiB
4.2 KiB
title | id | challengeType |
---|---|---|
Top rank per group | 595011cba5a81735713873bd | 5 |
Description
Find the top N ranked data in each group, where N is provided as a parameter. Name of the rank and the group are also provided as parameter.
Given the following data:[ { name: 'Tyler Bennett', id: 'E10297', salary: 32000, dept: 'D101' }, { name: 'John Rappl', id: 'E21437', salary: 47000, dept: 'D050' }, { name: 'George Woltman', id: 'E00127', salary: 53500, dept: 'D101' }, { name: 'Adam Smith', id: 'E63535', salary: 18000, dept: 'D202' }, { name: 'Claire Buckman', id: 'E39876', salary: 27800, dept: 'D202' }, { name: 'David McClellan', id: 'E04242', salary: 41500, dept: 'D101' }, { name: 'Rich Holcomb', id: 'E01234', salary: 49500, dept: 'D202' }, { name: 'Nathan Adams', id: 'E41298', salary: 21900, dept: 'D050' }, { name: 'Richard Potter', id: 'E43128', salary: 15900, dept: 'D101' }, { name: 'David Motsinger', id: 'E27002', salary: 19250, dept: 'D202' }, { name: 'Tim Sampair', id: 'E03033', salary: 27000, dept: 'D101' }, { name: 'Kim Arlich', id: 'E10001', salary: 57000, dept: 'D190' }, { name: 'Timothy Grove', id: 'E16398', salary: 29900, dept: 'D190' } ];one could rank top 10 employees in each department by calling
topRankPerGroup(10, data, 'dept', 'salary')
Given the following data:
[ { name: 'Friday 13th', genre: 'horror', rating: 9.9 }, { name: "Nightmare on Elm's Street", genre: 'horror', rating: 5.7 }, { name: 'Titanic', genre: 'drama', rating: 7.3 }, { name: 'Maze Runner', genre: 'scifi', rating: 7.1 }, { name: 'Blade runner', genre: 'scifi', rating: 8.9 } ];one could rank the top-rated movie in each genre by calling
topRankPerGroup(1, data, 'genre', 'rating')
Instructions
Tests
tests:
- text: <code>topRankPerGroup</code> is a function.
testString: 'assert(typeof topRankPerGroup === "function", "<code>topRankPerGroup</code> is a function.");'
- text: <code>topRankPerGroup</code> returns undefined on negative n values.
testString: 'assert(typeof topRankPerGroup(-1, []) === "undefined", "<code>topRankPerGroup</code> returns undefined on negative n values.");'
- text: First department must be D050
testString: 'assert.equal(res1[0][0].dept, "D050", "First department must be D050");'
- text: First department must be D050
testString: 'assert.equal(res1[0][1].salary, 21900, "First department must be D050");'
- text: The last department must be D202
testString: 'assert.equal(res1[3][3].dept, "D202", "The last department must be D202");'
- text: '<code>topRankPerGroup(1, ...)</code> must return only top ranking result per group.'
testString: 'assert.equal(res2[2].length, 1, "<code>topRankPerGroup(1, ...)</code> must return only top ranking result per group.");'
- text: '<code>topRankPerGroup(1, ...)</code> must return only top ranking result per group.'
testString: 'assert.equal(res3[2][1].name, "Maze Runner", "<code>topRankPerGroup(1, ...)</code> must return only top ranking result per group.");'
Challenge Seed
function topRankPerGroup(n, data, groupName, rankName) {
// Good luck!
return true;
}
After Test
console.info('after the test');
Solution
const collectDept = function (arrOfObj, groupName) {
const collect = arrOfObj.reduce((rtnObj, obj) => {
if (rtnObj[obj[groupName]] === undefined) {
rtnObj[obj[groupName]] = [];
}
rtnObj[obj[groupName]].push(obj);
return rtnObj;
}, {} // initial value to reduce
);
return Object.keys(collect).sort().map(key => collect[key]);
};
const sortRank = function (arrOfRankArrs, rankName) {
return arrOfRankArrs.map(item => item.sort((a, b) => {
if (a[rankName] > b[rankName]) { return -1; }
if (a[rankName] < b[rankName]) { return 1; }
return 0;
}));
};
function topRankPerGroup(n, data, groupName, rankName) {
if (n < 0) { return; }
return sortRank(collectDept(data, groupName),
rankName).map(list => list.slice(0, n));
}