average aggregation functionality added

README.md

@@ -99,6 +99,7 @@ Instead of extends the Model class in your models extend the Elasticsearch to us
     e) sum_bucket
     f) sum
     d) date_histogram (with interval option [default - month])
+    e) avg
 
 
 5. sort - Sort the query result

src/AggregationClause.php

@@ -136,6 +136,19 @@ public function sum($field)
         return $this;
     }
 
+    /**
+     * Gives the avg value of a field
+     * @param  string $field Field Name
+     * @return  Tamizh\LaravelEs\AggregationClause
+     */
+    public function avg($field)
+    {
+        $this->field = $field;
+        $this->type = "avg";
+        $this->aggs_array[$this->type]['field'] = $this->field;
+        return $this;
+    }
+
     /**
      * Size of the aggregation
      * @param  integer  $size  Size of the aggregation result