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---
id: 595011cba5a81735713873bd
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title: Classifica superiore per gruppo
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challengeType: 5
forumTopicId: 302339
dashedName: top-rank-per-group
---
# --description--
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Trova i primi `n` dati classificati in ogni gruppo, dove `n` è fornito come parametro. Anche il nome del rango e del gruppo sono forniti come parametri.
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Forniti i seguenti dati:
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```js
testData1 = [
{ 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' }
];
```
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Si potrebbero classificare i primi 10 dipendenti in ogni reparto chiamando:
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```js
topRankPerGroup(10, testData1, 'dept', 'salary')
```
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Forniti i seguenti dati:
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```js
testData2 = [
{ 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 }
];
```
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Si potrebbe classificare il film più votato in ogni genere chiamando:
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```js
topRankPerGroup(1, testData2, 'genre', 'rating')
```
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La funzione dovrebbe restituire un array con un array per ogni gruppo contenente gli `n` oggetti superiori.
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Per esempio, dati:
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```js
[
{ name: 'Claire Buckman', id: 'E39876', salary: 27800, dept: 'D101' },
{ name: 'Rich Holcomb', id: 'E01234', salary: 49500, dept: 'D050' },
{ name: 'David Motsinger', id: 'E27002', salary: 19250, dept: 'D050' },
{ name: 'Tim Sampair', id: 'E03033', salary: 27000, dept: 'D101' },
{ name: 'Kim Arlich', id: 'E10001', salary: 57000, dept: 'D050' },
{ name: 'Timothy Grove', id: 'E16398', salary: 29900, dept: 'D101' }
];
```
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I primi due dipendenti in classifica per stipendio in ogni reparto saranno:
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```js
[ [ { name: 'Kim Arlich', id: 'E10001', salary: 57000, dept: 'D050' },
{ name: 'Rich Holcomb', id: 'E01234', salary: 49500, dept: 'D050' } ],
[ { name: 'Timothy Grove', id: 'E16398', salary: 29900, dept: 'D101' },
{ name: 'Claire Buckman', id: 'E39876', salary: 27800, dept: 'D101' } ] ]
```
# --hints--
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`topRankPerGroup` dovrebbe essere una funzione.
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```js
assert(typeof topRankPerGroup === 'function');
```
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`topRankPerGroup` dovrebbe restituire undefined per i valori negativi di n.
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```js
assert(typeof topRankPerGroup(-1, []) === 'undefined');
```
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Per `topRankPerGroup(10, testData1, 'dept', 'salary')` , il primo risultato nel primo gruppo dovrebbe essere `{ name: 'John Rappl', id: 'E21437', salary: 47000, dept: 'D050'}` .
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```js
assert.deepEqual(res1[0][0], { name: 'John Rappl', id: 'E21437', salary: 47000, dept: 'D050'});
```
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Per `topRankPerGroup(10, testData1, 'dept', 'salary')` , l'ultimo risultato nell'ultimo gruppo dovrebbe essere `{ name: 'Adam Smith', id: 'E63535', salary: 18000, dept: 'D202' }` .
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```js
assert.deepEqual(res1[3][3], { name: 'Adam Smith', id: 'E63535', salary: 18000, dept: 'D202' });
```
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`topRankPerGroup(1, ...)` dovrebbe restituire solo il il primo risultato in classifica per ogni gruppo.
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```js
assert.equal(res2[2].length, 1);
```
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`topRankPerGroup(2, ...)` dovrebbe restituire due risultati di classifica per gruppo.
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```js
assert.equal(res3[2][1].name, 'Maze Runner');
```
# --seed--
## --after-user-code--
```js
const testData1 = [
{ 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' }
];
const res1 = topRankPerGroup(10, testData1, 'dept', 'salary');
const testData2 = [
{ 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 }
];
const res2 = topRankPerGroup(1, testData2, 'genre', 'rating');
const res3 = topRankPerGroup(2, testData2, 'genre', 'rating');
```
## --seed-contents--
```js
function topRankPerGroup(n, data, groupName, rankName) {
return true;
}
```
# --solutions--
```js
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));
}
```