[5.8] Add countBy method to Collection

src/Illuminate/Support/Collection.php

@@ -1890,6 +1890,28 @@ public function count()
         return count($this->items);
     }
 
+    /**
+     * Count the number of items in the collection by some predicate.
+     *
+     * @param callable|null
+     * @return static
+     */
+    public function countBy($predicate = null)
+    {
+        if (is_null($predicate)) {
+            $predicate = function ($val) {
+                return $val;
+            };
+        }
+
+        return new static(
+            $this->groupBy($predicate)
+                ->map(function ($val) {
+                    return $val->count();
+                })
+        );
+    }
+
     /**
      * Add an item to the collection.
      *

tests/Support/SupportCollectionTest.php

@@ -307,6 +307,31 @@ public function testCountable()
         $this->assertCount(2, $c);
     }
 
+    public function testCountableByWithoutPredicate()
+    {
+        $c = new Collection(['foo', 'foo', 'foo', 'bar', 'bar', 'foobar']);
+        $this->assertEquals(['foo' => 3, 'bar' => 2, 'foobar' => 1], $c->countBy()->all());
+
+        $c = new Collection([true, true, false, false, false]);
+        $this->assertEquals([true => 2, false => 3], $c->countBy()->all());
+
+        $c = new Collection([1, 5, 1, 5, 5, 1]);
+        $this->assertEquals([1 => 3, 5 => 3], $c->countBy()->all());
+    }
+
+    public function testCountableByWithPredicate()
+    {
+        $c = new Collection(['alice', 'aaron', 'bob', 'carla']);
+        $this->assertEquals(['a' => 2, 'b' => 1, 'c' => 1], $c->countBy(function ($name) {
+            return substr($name, 0, 1);
+        })->all());
+
+        $c = new Collection([1, 2, 3, 4, 5]);
+        $this->assertEquals([true => 2, false => 3], $c->countBy(function ($i) {
+            return $i % 2 === 0;
+        })->all());
+    }
+
     public function testIterable()
     {
         $c = new Collection(['foo']);