added zip

PhpCollection.php

@@ -105,6 +105,21 @@ public function exclude($keys)
         return new PhpCollection($arData);
     }
 
+    public function zip($array){
+        $arData = [];
+
+        $arCollection = array_values($this->arCollection);
+        $nCount = count($arCollection);
+
+        for ($nIndex = 0; $nIndex < $nCount; $nIndex++) {
+            $arFirstItem = is_array($arCollection[$nIndex]) ? $arCollection[$nIndex] : [$arCollection[$nIndex]];
+            $arSecondItem = is_array($array[$nIndex]) ? $array[$nIndex] : [$array[$nIndex]];
+            $arData[] = array_merge($arFirstItem, $arSecondItem);
+        }
+
+        return new PhpCollection($arData);
+    }
+
     /**
      * @param string $glue
      * @param string $serializer
@@ -167,8 +182,8 @@ public function map($function = false)
             };
         }
         $arData = [];
-        foreach ($this->arCollection as $arItem) {
-            $arData[] = $function($arItem);
+        foreach ($this->arCollection as $sKey => $arItem) {
+            $arData[$sKey] = $function($arItem, $sKey);
         }
         return new PhpCollection($arData);
     }

README.md

@@ -7,6 +7,22 @@ inspired by Illuminate\Support\Collection and Lodash
 composer require izica/php-collection
 ```
 
+### Notice
+Every method create new collection, not mutate data;
+
+```php
+
+$collection = PhpCollection:collect([100, 200, 300, 400]);
+$collection2 = $collection->filter(function($item){
+    return $item > 200;
+})
+
+/*
+    $collection != $collection2
+*/
+
+```
+
 ### Documentation
 
 * [collect](#collectarray)
@@ -241,7 +257,7 @@ $collection = PhpCollection:collect($products)->groupBy('category_id')->all();
 #### count()
 #### all() OR toArray()
 #### toJson()
-
+#### zip()
 
 ## TODO
 #### dumpBrowser()