docstr: Read relations from parquet file.
  Schema should be the following:
  "id1"(string), "id2"(string) and "label"(int).
  
  :param path: The path to the parquet file.
  :param sc: An instance of SparkContext.
  :return: RDD of Relation.
docstr_tok: ["Read","relations","from","parquet","file",".","Schema","should","be","the","following",":","''","id1","''","(","string",")",",","``","id2","''","(","string",")","and","``","label","''","(","int",")",".",":","param","path",":","The","path","to","the","parquet","file",".",":","param","sc",":","An","instance","of","SparkContext",".",":","return",":","RDD","of","Relation","."]
code: def read_parquet(path, sc, bigdl_type="float"):
      """
      Read relations from parquet file.
      Schema should be the following:
      "id1"(string), "id2"(string) and "label"(int).
  
      :param path: The path to the parquet file.
      :param sc: An instance of SparkContext.
      :return: RDD of Relation.
      """
      jvalue = callZooFunc(bigdl_type, "readRelationsParquet", path, sc)
      return jvalue.map(
          lambda x: Relation(str(x[0]), str(x[1]), int(x[2]))
      )
  
imports: from bigdl.util.common import *
  from zoo.common.utils import callZooFunc
  from bigdl.dataset.dataset import DataSet
  from pyspark.serializers import CloudPickleSerializer
  import sys
  import math
  import warnings
label_desc: Use image node_id 2 for calling the Relations obj's underlying member method code with example usage: obj.read_parquet(path, sc, bigdl_type) and returns: jvalue