193 lines
6.1 KiB
Markdown
193 lines
6.1 KiB
Markdown
---
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id: 595011cba5a81735713873bd
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title: Top rank per group
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challengeType: 5
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forumTopicId: 302339
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dashedName: top-rank-per-group
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---
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# --description--
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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.
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Given the following data:
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```js
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testData1 = [
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{ name: 'Tyler Bennett', id: 'E10297', salary: 32000, dept: 'D101' },
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{ name: 'John Rappl', id: 'E21437', salary: 47000, dept: 'D050' },
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{ name: 'George Woltman', id: 'E00127', salary: 53500, dept: 'D101' },
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{ name: 'Adam Smith', id: 'E63535', salary: 18000, dept: 'D202' },
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{ name: 'Claire Buckman', id: 'E39876', salary: 27800, dept: 'D202' },
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{ name: 'David McClellan', id: 'E04242', salary: 41500, dept: 'D101' },
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{ name: 'Rich Holcomb', id: 'E01234', salary: 49500, dept: 'D202' },
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{ name: 'Nathan Adams', id: 'E41298', salary: 21900, dept: 'D050' },
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{ name: 'Richard Potter', id: 'E43128', salary: 15900, dept: 'D101' },
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{ name: 'David Motsinger', id: 'E27002', salary: 19250, dept: 'D202' },
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{ name: 'Tim Sampair', id: 'E03033', salary: 27000, dept: 'D101' },
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{ name: 'Kim Arlich', id: 'E10001', salary: 57000, dept: 'D190' },
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{ name: 'Timothy Grove', id: 'E16398', salary: 29900, dept: 'D190' }
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];
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```
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One could rank top 10 employees in each department by calling:
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```js
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topRankPerGroup(10, testData1, 'dept', 'salary')
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```
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Given the following data:
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```js
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testData2 = [
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{ name: 'Friday 13th', genre: 'horror', rating: 9.9 },
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{ name: "Nightmare on Elm's Street", genre: 'horror', rating: 5.7 },
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{ name: 'Titanic', genre: 'drama', rating: 7.3 },
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{ name: 'Maze Runner', genre: 'scifi', rating: 7.1 },
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{ name: 'Blade runner', genre: 'scifi', rating: 8.9 }
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];
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```
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One could rank the top-rated movie in each genre by calling:
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```js
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topRankPerGroup(1, testData2, 'genre', 'rating')
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```
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The function should return an array with an array for each group containing the top `n` objects.
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For example, given data:
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```js
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[
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{ name: 'Claire Buckman', id: 'E39876', salary: 27800, dept: 'D101' },
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{ name: 'Rich Holcomb', id: 'E01234', salary: 49500, dept: 'D050' },
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{ name: 'David Motsinger', id: 'E27002', salary: 19250, dept: 'D050' },
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{ name: 'Tim Sampair', id: 'E03033', salary: 27000, dept: 'D101' },
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{ name: 'Kim Arlich', id: 'E10001', salary: 57000, dept: 'D050' },
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{ name: 'Timothy Grove', id: 'E16398', salary: 29900, dept: 'D101' }
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];
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```
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Top two ranking employees in each department by salary would be:
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```js
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[ [ { name: 'Kim Arlich', id: 'E10001', salary: 57000, dept: 'D050' },
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{ name: 'Rich Holcomb', id: 'E01234', salary: 49500, dept: 'D050' } ],
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[ { name: 'Timothy Grove', id: 'E16398', salary: 29900, dept: 'D101' },
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{ name: 'Claire Buckman', id: 'E39876', salary: 27800, dept: 'D101' } ] ]
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```
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# --hints--
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`topRankPerGroup` should be a function.
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```js
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assert(typeof topRankPerGroup === 'function');
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```
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`topRankPerGroup` should return undefined on negative n values.
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```js
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assert(typeof topRankPerGroup(-1, []) === 'undefined');
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```
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For `topRankPerGroup(10, testData1, 'dept', 'salary')`, the first result in the first group should be `{ name: 'John Rappl', id: 'E21437', salary: 47000, dept: 'D050'}`.
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```js
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assert.deepEqual(res1[0][0], { name: 'John Rappl', id: 'E21437', salary: 47000, dept: 'D050'});
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```
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For `topRankPerGroup(10, testData1, 'dept', 'salary')`, the last result in the last group should be `{ name: 'Adam Smith', id: 'E63535', salary: 18000, dept: 'D202' }`.
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```js
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assert.deepEqual(res1[3][3], { name: 'Adam Smith', id: 'E63535', salary: 18000, dept: 'D202' });
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```
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`topRankPerGroup(1, ...)` should return only top ranking result per group.
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```js
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assert.equal(res2[2].length, 1);
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```
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`topRankPerGroup(2, ...)` should return two ranking results per group.
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```js
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assert.equal(res3[2][1].name, 'Maze Runner');
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```
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# --seed--
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## --after-user-code--
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```js
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const testData1 = [
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{ name: 'Tyler Bennett', id: 'E10297', salary: 32000, dept: 'D101' },
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{ name: 'John Rappl', id: 'E21437', salary: 47000, dept: 'D050' },
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{ name: 'George Woltman', id: 'E00127', salary: 53500, dept: 'D101' },
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{ name: 'Adam Smith', id: 'E63535', salary: 18000, dept: 'D202' },
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{ name: 'Claire Buckman', id: 'E39876', salary: 27800, dept: 'D202' },
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{ name: 'David McClellan', id: 'E04242', salary: 41500, dept: 'D101' },
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{ name: 'Rich Holcomb', id: 'E01234', salary: 49500, dept: 'D202' },
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{ name: 'Nathan Adams', id: 'E41298', salary: 21900, dept: 'D050' },
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{ name: 'Richard Potter', id: 'E43128', salary: 15900, dept: 'D101' },
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{ name: 'David Motsinger', id: 'E27002', salary: 19250, dept: 'D202' },
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{ name: 'Tim Sampair', id: 'E03033', salary: 27000, dept: 'D101' },
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{ name: 'Kim Arlich', id: 'E10001', salary: 57000, dept: 'D190' },
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{ name: 'Timothy Grove', id: 'E16398', salary: 29900, dept: 'D190' }
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];
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const res1 = topRankPerGroup(10, testData1, 'dept', 'salary');
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const testData2 = [
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{ name: 'Friday 13th', genre: 'horror', rating: 9.9 },
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{ name: "Nightmare on Elm's Street", genre: 'horror', rating: 5.7 },
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{ name: 'Titanic', genre: 'drama', rating: 7.3 },
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{ name: 'Maze Runner', genre: 'scifi', rating: 7.1 },
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{ name: 'Blade runner', genre: 'scifi', rating: 8.9 }
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];
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const res2 = topRankPerGroup(1, testData2, 'genre', 'rating');
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const res3 = topRankPerGroup(2, testData2, 'genre', 'rating');
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```
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## --seed-contents--
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```js
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function topRankPerGroup(n, data, groupName, rankName) {
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return true;
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}
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```
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# --solutions--
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```js
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const collectDept = function (arrOfObj, groupName) {
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const collect = arrOfObj.reduce((rtnObj, obj) => {
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if (rtnObj[obj[groupName]] === undefined) {
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rtnObj[obj[groupName]] = [];
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}
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rtnObj[obj[groupName]].push(obj);
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return rtnObj;
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}, {} // initial value to reduce
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);
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return Object.keys(collect).sort().map(key => collect[key]);
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};
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const sortRank = function (arrOfRankArrs, rankName) {
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return arrOfRankArrs.map(item => item.sort((a, b) => {
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if (a[rankName] > b[rankName]) { return -1; }
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if (a[rankName] < b[rankName]) { return 1; }
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return 0;
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}));
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};
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function topRankPerGroup(n, data, groupName, rankName) {
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if (n < 0) { return; }
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return sortRank(collectDept(data, groupName),
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rankName).map(list => list.slice(0, n));
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}
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```
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