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Shorter stableSort example and test

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simov
2018-02-11 15:56:19 +02:00
parent 852455fd43
commit 8b7dd96474
2 changed files with 8 additions and 73 deletions
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41
snippets/stableSort.md
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@ -14,40 +14,7 @@ const stableSort = (arr, compare) =>
``` ```
```js ```js
// sorted by weight const arr = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
const input = [ const stable = stableSort(arr, () => 0); // [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
{ height: 100, weight: 80 }, const unstable = [...arr].sort(() => 0); // [5, 0, 2, 3, 4, 1, 6, 7, 8, 9, 10] (in Chrome/NodeJS)
{ height: 90, weight: 90 }, ```
{ height: 70, weight: 95 },
{ height: 100, weight: 100 },
{ height: 80, weight: 110 },
{ height: 110, weight: 115 },
{ height: 100, weight: 120 },
{ height: 70, weight: 125 },
{ height: 70, weight: 130 },
{ height: 100, weight: 135 },
{ height: 75, weight: 140 },
{ height: 70, weight: 140 }
];
// sort by height
stableSort(input, (a, b) => a.height - b.height);
/*
Items with the same height are still sorted by weight
which means they preserved their relative order.
[
{ height: 70, weight: 95 },
{ height: 70, weight: 125 },
{ height: 70, weight: 130 },
{ height: 70, weight: 140 },
{ height: 75, weight: 140 },
{ height: 80, weight: 110 },
{ height: 90, weight: 90 },
{ height: 100, weight: 80 },
{ height: 100, weight: 100 },
{ height: 100, weight: 120 },
{ height: 100, weight: 135 },
{ height: 110, weight: 115 }
]
*/

40
test/stableSort/stableSort.test.js
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@ -10,44 +10,12 @@ test('Testing stableSort', (t) => {
//t.false(stableSort(args..), 'Expected'); //t.false(stableSort(args..), 'Expected');
//t.throws(stableSort(args..), 'Expected'); //t.throws(stableSort(args..), 'Expected');
// sorted by weight const arr = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
const input = [ const compare = () => 0;
{ height: 100, weight: 80 },
{ height: 90, weight: 90 },
{ height: 70, weight: 95 },
{ height: 100, weight: 100 },
{ height: 80, weight: 110 },
{ height: 110, weight: 115 },
{ height: 100, weight: 120 },
{ height: 70, weight: 125 },
{ height: 70, weight: 130 },
{ height: 100, weight: 135 },
{ height: 75, weight: 140 },
{ height: 70, weight: 140 }
]
// sorted by height (using stableSort)
const target = [
{ height: 70, weight: 95 },
{ height: 70, weight: 125 },
{ height: 70, weight: 130 },
{ height: 70, weight: 140 },
{ height: 75, weight: 140 },
{ height: 80, weight: 110 },
{ height: 90, weight: 90 },
{ height: 100, weight: 80 },
{ height: 100, weight: 100 },
{ height: 100, weight: 120 },
{ height: 100, weight: 135 },
{ height: 110, weight: 115 }
]
const compare = (a, b) => a.height - b.height;
// stable // stable
t.deepEqual(stableSort(input, compare), target); t.deepEqual(stableSort(arr, compare), arr);
// unstable // unstable
t.notDeepEqual(input.sort(compare), target); t.notDeepEqual([...arr].sort(compare), arr);
t.end(); t.end();
}); });