Add aperture

snippets/aperture.md

@@ -0,0 +1,22 @@
+---
+title: aperture
+tags: array,intermediate
+---
+
+Returns an array of `n`-tuples of consecutive elements.
+
+Use `Array.prototype.slice()` and `Array.prototype.map()` to create an array of appropriate length and populate it with `n`-tuples of consecutive elements from `arr`.
+If `n` is greater than the length of `arr`, return an empty array.
+
+```js
+const aperture = (n, arr) =>
+  n > arr.length
+    ? []
+    : arr.slice(n - 1).map((v, i) => [...arr.slice(i, i + n - 1), v]);
+```
+
+```js
+R.aperture(2, [1, 2, 3, 4]); // [[1, 2], [2, 3], [3, 4]]
+R.aperture(3, [1, 2, 3, 4]); // [[1, 2, 3], [2, 3, 4]]
+R.aperture(5, [1, 2, 3, 4]); // []
+```