Merge pull request #1921 from o1-labs/features/arrays/pad_zip

[easy] Added `zip` and `pad` functionalities for arrays

src/lib/util/arrays.ts

@@ -1,9 +1,12 @@
 import { assert } from './errors.js';
 
-export { chunk, chunkString };
+export { chunk, chunkString, zip, pad };
 
 function chunk<T>(array: T[], size: number): T[][] {
-  assert(array.length % size === 0, 'invalid input length');
+  assert(
+    array.length % size === 0,
+    `chunk(): invalid input length, it must be a multiple of ${size}`
+  );
   return Array.from({ length: array.length / size }, (_, i) =>
     array.slice(size * i, size * (i + 1))
   );
@@ -12,3 +15,19 @@ function chunk<T>(array: T[], size: number): T[][] {
 function chunkString(str: string, size: number): string[] {
   return chunk([...str], size).map((c) => c.join(''));
 }
+
+function zip<T, S>(a: T[], b: S[]) {
+  assert(
+    a.length <= b.length,
+    'zip(): second array must be at least as long as the first array'
+  );
+  return a.map((a, i): [T, S] => [a, b[i]!]);
+}
+
+function pad<T>(array: T[], size: number, value: T): T[] {
+  assert(
+    array.length <= size,
+    `target size ${size} should be greater or equal than the length of the array ${array.length}`
+  );
+  return array.concat(Array.from({ length: size - array.length }, () => value));
+}