golang 解析json字符串问题

处理prometheus http api 返回的json字符串 遇到解析问题

{
   "status" : "success",
   "data" : {
      "resultType" : "matrix",
      "result" : [
         {
            "metric" : {
               "__name__" : "up",
               "job" : "prometheus",
               "instance" : "localhost:9090"
            },
            "values" : [
               [ 1435781430.781, "1" ],
               [ 1435781445.781, "1" ],
               [ 1435781460.781, "1" ]
            ]
         },
         {
            "metric" : {
               "__name__" : "up",
               "job" : "node",
               "instance" : "localhost:9091"
            },
            "values" : [
               [ 1435781430.781, "0" ],
               [ 1435781445.781, "0" ],
               [ 1435781460.781, "1" ]
            ]
         }
      ]
   }

上述json字符串中 values字段 在prometheus里定义是matrix类型 这种要怎么解析呢 既不是struct 也不是[]string

实际上就是解析类似于{"values":[[123,"0"],[456,"1"]]} 这种json字符串 golang要怎么解析成类似于数组的类型 可以按index读取？

虽然可以直接用map[string]interface{} 来反序列化 但这样也无法按行读取到value的值