code: def jsonFile(self, path, schema=None, sampling_ratio=1.0):
          
          schema_rdd = self.sql_ctx.jsonFile(path, schema, sampling_ratio)
          return self.from_spark_rdd(schema_rdd)
docs: Loads a text file storing one JSON object per line as a
          L{DataFrame}.
          Parameters
          ----------
          path: string
               The path of the json files to load. Should be Hadoop style
               paths (e.g. hdfs://..., file://... etc.).
          schema: StructType, optional
               If you know the schema of your input data you can specify it. The
               schema is specified using Spark SQL's schema format. If not
               specified will sample the json records to determine the schema.
               Spark SQL's schema format is documented (somewhat) in the
               "Programmatically Specifying the Schema" of the Spark SQL
               programming guide at: http://bit.ly/sparkSQLprogrammingGuide
          sampling_ratio: int, default=1.0
               Percentage of the records to sample when infering schema.
               Defaults to all records for safety, but you may be able to set to
               a lower ratio if the same fields are present accross records or
               your input is of sufficient size.
          Returns
          -------
          A L{DataFrame} of the contents of the json files.