Stack Overflow
Stack Overflow

Questions tagged [mapper]

The mapper is the first step in MapReduce framework, a component of a larger scalable, parallel-izable algorithm.

Maps input key/value pairs to a set of intermediate key/value pairs.

Maps are the individual tasks which transform input records into a intermediate records. The transformed intermediate records need not be of the same type as the input records. A given input pair may map to zero or many output pairs.

The most common map reduce framework is Apache Hadoop.

See also MapReduce Wiki.

653 questions
-1
votes
2 answers

Implementing R programs in hadoop System

I have written Mapper and Reducer programs using R language. I am using the Hadoop streaming utility to execute the R programs on hadoop. My constraint is that i need to input 2 text files to the mapper program. How to achieve it? Kindly assist at…
user2500875
  • 33
  • 1
  • 2
  • 8
-2
votes
2 answers

Creating a mapper that find the capitalized words in a text

Implement filescounter, which takes a string in any variety and returns the number of capitalized words in that string, inclusive of the last and first character. def filescounter(s): sr=0 for words in text: #... return sr I'm…
Poooo Jooo
  • 1
  • 1
-2
votes
1 answer

Topological Data Analysis (TDA) Mapper for Python

I am doing a beginner course in Topological Data Analysis and my instructor insists that I use Python for my analysis. I am on Jupyter notebook editor. I am confused about the Mapper for Python as I can’t find any tutorial documentation about using…
THABELO
  • 1
  • 1
-3
votes
2 answers

Return object as Json in java

We would like to return Object class as JSON string public static String genJson(Response r, Auth auth) { Auth p = new Auth(); ObjectMapper mapper = new ObjectMapper(); String transactionResult =…
Hoo
  • 1,806
  • 7
  • 33
  • 66
-3
votes
1 answer

Morphia Mapper Exception for Object fields

This is the error which I'm getting java.lang.ClassCastException: java.lang.Integer cannot be cast to com.mongodb.DBObject Here's my POJO @Entity("cars") @Getter @Setter public class Car { @Id private ObjectId id; private String…
Prozac
  • 25
  • 1
  • 3
-3
votes
1 answer

Does Hadoop use HBase as an "auxiliar" between the map and the reduce step?

Or HBase does not have anything to do with this process? I have read that Hbase works on top of hadoop, and I have seen some diagrams that shows Hbase as part of the MapReduce part of Hadoop, but I have not found anything concrete about my question.
Sergio Adrián Lagunas Pinacho
  • 18
  • 5
-4
votes
1 answer

How to takes a list of objects of something type and return list of objects of different type

I have a problem. I want to write a method which as an argument takes a list of objects of type A, some mapper which change this and returns a list of objects of type B For example: List date = mapTo (Arrays.asList ("2014-01-01",…
borkovicz
  • 11
  • 2
1 2 3
…
43
44