py4j

I want to call java from python with Py4J library, from py4j.java_gateway import JavaGateway gateway = JavaGateway() # connect to the JVM gateway.jvm.java.lang.System.out.println('Hello World!') I've got the following error: "Py4JNetworkError: An error occurred while trying to connect to the Java server". It's seems that no JVM is running, how to fix that? package test.test; import py4j.GatewayServer; public class AdditionApplication { public int addition(int first, int second) { return first + second; } public static void main(String[] args) { AdditionApplication app = new AdditionApplication

I'm trying to extend the example from this tutorial by sending Python objects to Java. While the example code which exchanges String objects between Python and Java works fine, when I try to replace it with my own Python object (Event), an error regarding object_id is displayed. Python Code: class Event(object): #some content here stack = gateway.entry_point.getStack() event = Event() stack.push(event) Error: Traceback (most recent call last): File "/home/******/src/py4jSample.py", line 19, in <module> stack.push(event) File "/usr/local/lib/python2.7/dist-packages/py4j-0.7-py2.7.egg/py4j/java

pycharm搭建spark环境 安装python环境 windows下有安装包，自行下载安装即可 安装spark环境 官网下载 spark-2.3.1-bin-hadoop2.7 包，解压即可 配置 HADOOP_HOME:D:\softwares\Java\hadoop-2.7.7 SPARK_HOME:D:\softwares\Java\spark-2.3.1-bin-hadoop2.7 PATH:%SPARK_HOME%\bin;%HADOOP_HOME%\bin; 配置python-spark环境 将spark目录 D:\softwares\Java\spark-2.3.1-bin-hadoop2.7\python\lib 下的 py4j-0.10.7-src.zip 解压 将解压后的 py4j 放到 python 目录 D:\softwares\Java\Python36\Lib\site-packages 下 提示：python 和 spark 的安装目录自行替换 下载安装pycharm 创建项目 创建python文件，内容如下： from pyspark import SparkConf, SparkContext conf = SparkConf().setMaster('local').setAppName('JackManWu') sc =

I am quite new to python and am trying to call python's function from java. My primary requirements are these: call should be transparent, in the sense that it should not require modifying .py file simply to enable it to be called from java. I might be given any python file with some functions inside it. I should be able to call any of these functions without requiring to modify .py file. I want to be able to send arguments of both primitive types ( int , String , floats etc.) or non primitive types ( HashMap , ArrayList ) from java to python function and receive back the returned object

I'm trying to run a custom HDFS reader class in PySpark. This class is written in Java and I need to access it from PySpark, either from the shell or with spark-submit. In PySpark, I retrieve the JavaGateway from the SparkContext ( sc._gateway ). Say I have a class: package org.foo.module public class Foo { public int fooMethod() { return 1; } } I've tried to package it into a jar and pass it with the --jar option to pyspark and then running: from py4j.java_gateway import java_import jvm = sc._gateway.jvm java_import(jvm, "org.foo.module.*") foo = jvm.org.foo.module.Foo() But I get the error:

This question is directed towards persons familiar with py4j - and can help to resolve a pickling error. I am trying to add a method to the pyspark PythonMLLibAPI that accepts an RDD of a namedtuple, does some work, and returns a result in the form of an RDD. This method is modeled after the PYthonMLLibAPI.trainALSModel() method, whose analogous existing relevant portions are: def trainALSModel( ratingsJRDD: JavaRDD[Rating], .. ) The existing python Rating class used to model the new code is: class Rating(namedtuple("Rating", ["user", "product", "rating"])): def __reduce__(self): return Rating