## unique方法 返回集合中所有唯一的项目 # unique方法 返回集合中所有唯一的项目。返回的集合保留着原数组的键，所以在这个例子中，我们会使用[values](https://www.kancloud.cn/collections/values.md)方法来把键重置为连续编号的索引。 ~~~ $collection = collect([1, 1, 2, 2, 3, 4, 2]); $unique = $collection->unique(); // [ 0 => 1, 2 => 2, 4 => 3, 5 => 4]; $unique->values()->all(); // [1, 2, 3, 4] ~~~ 处理嵌套数组或对象时，你可以指定用来决定唯一性的键： ~~~ $collection = collect([ ['name' => 'iPhone 6', 'brand' => 'Apple', 'type' => 'phone'], ['name' => 'iPhone 5', 'brand' => 'Apple', 'type' => 'phone'], ['name' => 'Apple Watch', 'brand' => 'Apple', 'type' => 'watch'], ['name' => 'Galaxy S6', 'brand' => 'Samsung', 'type' => 'phone'], ['name' => 'Galaxy Gear', 'brand' => 'Samsung', 'type' => 'watch'], ]); $unique = $collection->unique('brand'); $unique->values()->all(); /* [ ['name' => 'iPhone 6', 'brand' => 'Apple', 'type' => 'phone'], ['name' => 'Galaxy S6', 'brand' => 'Samsung', 'type' => 'phone'], ] */ ~~~ 你也可以传入自己的回调来确定项目的唯一性： ~~~ $collection = collect([ ['name' => 'iPhone 6', 'brand' => 'Apple', 'type' => 'phone'], ['name' => 'iPhone 5', 'brand' => 'Apple', 'type' => 'phone'], ['name' => 'Apple Watch', 'brand' => 'Apple', 'type' => 'watch'], ['name' => 'Galaxy S6', 'brand' => 'Samsung', 'type' => 'phone'], ['name' => 'Galaxy Gear', 'brand' => 'Samsung', 'type' => 'watch'], ]); $unique = $collection->unique(function ($item) { return $item['brand'].$item['type']; }); $unique->values()->all(); /* [ ['name' => 'iPhone 6', 'brand' => 'Apple', 'type' => 'phone'], ['name' => 'Apple Watch', 'brand' => 'Apple', 'type' => 'watch'], ['name' => 'Galaxy S6', 'brand' => 'Samsung', 'type' => 'phone'], ['name' => 'Galaxy Gear', 'brand' => 'Samsung', 'type' => 'watch'], ] */ ~~~ > 在检查项目值时`unique`方法使用的是「宽松」比较，意味着具有整数值的字符串将被视为等于相同值的整数。使用[uniqueStrict](https://www.kancloud.cn/collections/uniqueStrict.md)可以进行「严格」比较 。