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Apache Spark: How can i access nested array of integers within Tuple2 object in Java?


Apache Spark: How can i access nested array of integers within Tuple2 object in Java?

By : user2948522
Date : November 14 2020, 04:51 PM
hope this fix your issue I am new to spark and i am trying to perform a mapping of words to counts and errors for the implementation of Space Saving Algorithm. For every word i need to keeps its counts and its errors. My code the following. The problem is that i cannot access the elements in array of integers within tuple2. , change this:
code :
for (Tuple2<?, ?> tuple : output) {
    Integer temp = (Integer) tuple._2()[0];  ///ERROR, HOW CAN I ACCESS ARRAY ELEMENT???
    System.out.println(tuple._1() + ": " + tuple._2()+" "+temp[0]);
}
for (Tuple2<String, Integer[]> tuple : output) {
    Integer temp = tuple._2()[0];
    System.out.println(tuple._1() + ": " + tuple._2() + " " + temp[0]);
}


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Pattern matching Scala (key, Tuple2) values in reduceByKey() for Apache Spark

Pattern matching Scala (key, Tuple2) values in reduceByKey() for Apache Spark


By : sdadas
Date : March 29 2020, 07:55 AM
To fix this issue I have an RDD containing (stockName, stockValue) tuples. Many of the stocks are repeated and have differing values. , You can nest patterns to deconstruct (x, y) into ((x1, x2), (y1, y2))
code :
val partial = stocks.map {
  case (stock, value) => stock -> (value, 1)
}.reduceByKey {
  case ((value1, count1), (value2, count2)) => (value1 + value2, count1 + count2)
}
Parse Json Object with an Array and Map to Multiple Pairs with Apache Spark in Java

Parse Json Object with an Array and Map to Multiple Pairs with Apache Spark in Java


By : Gian
Date : March 29 2020, 07:55 AM
will be helpful for those in need I've googled it all day long and couldn't find straight answer, so ended up posting a question here. , If you load json data into a DataFrame:
code :
DataFrame df = sqlContext.read().json("/path/to/json");
df.select(
    df.col("device_id"),
    df.col("timestamp"),
    org.apache.spark.sql.functions.explode(df.col("rooms")).as("room")
);
{"device_id": "1", "timestamp": 1436941050, "rooms": ["Office", "Foyer"]}
{"device_id": "2", "timestamp": 1435677490, "rooms": ["Office", "Lab"]}
{"device_id": "3", "timestamp": 1436673850, "rooms": ["Office", "Foyer"]}
+---------+------+----------+
|device_id|  room| timestamp|
+---------+------+----------+
|        1|Office|1436941050|
|        1| Foyer|1436941050|
|        2|Office|1435677490|
|        2|   Lab|1435677490|
|        3|Office|1436673850|
|        3| Foyer|1436673850|
+---------+------+----------+
Apache Spark: In PairFlatMapFunction, how to add tuples back to the Iterable<Tuple2<Integer, String>> return

Apache Spark: In PairFlatMapFunction, how to add tuples back to the Iterable<Tuple2<Integer, String>> return


By : Myungho Shin
Date : March 29 2020, 07:55 AM
it fixes the issue I'm new to spark. I have been working on a code involving two datasets. Hence I started with a PairFlatMapFunction in which i'm doing the processing of a mapper. , !!
I have found the answer for this question.
code :
List<Tuple2<Integer, String>> result = new ArrayList<Tuple2<Integer, String>>();
result.add(new Tuple2<Integer, String>(keyValue, concat));
Can I return a Tuple2 from an apache spark UDF (in java)?

Can I return a Tuple2 from an apache spark UDF (in java)?


By : 677
Date : March 29 2020, 07:55 AM
hope this fix your issue I need a UDF2 that takes two arguments as input corresponding to two Dataframe columns of types String and mllib.linalg.Vector and return a Tuple2. IS this doable? if yes, how do I register this udf()? , There goes a schema which can be defined as follows:
code :
import org.apache.spark.sql.types.DataType;
import org.apache.spark.sql.types.DataTypes;
import org.apache.spark.mllib.linalg.VectorUDT;

List<StructField> fields = new ArrayList<>();
fields.add(DataTypes.createStructField("id", DataTypes.StringType, false));
fields.add(DataTypes.createStructField("features", new VectorUDT(), false));
DataType schema = DataTypes.createStructType(fields);
df.select(struct(col("id"), col("features"));
Spark Java - Why Tuple2 can not be argument of function in map?

Spark Java - Why Tuple2 can not be argument of function in map?


By : sharquise leshawn
Date : March 29 2020, 07:55 AM
this will help I used the Lambda Expressions and solved this problem.
This my sample code
code :
JavaPairRDD<Detection,Detection> allCombinations = currentLevelNodes.cartesian(nextLevelNodes);

JavaRDD<Segment> segmentRDD = allCombinations.map(tuple -> new Segment(tuple._1, tuple._2));
public Segment(Detection a, Detection b){
  this.distance = Math.sqrt(Math.pow(a.x-b.x, 2)+Math.pow(a.y-b.y, 2));
}
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