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1. Pattern matching Scala has a very powerful pattern matching mechanism and is widely used, such as: Judge fixed valueType queryGet data quickly 1.1 simple pattern matching A pattern matching contains a series of alternatives, each of which starts with the keyword case. Each alternative contains a pattern and one or more expressions. The a ...

Ranking statistics of Chinese Universities Based on MapReduce Overall thinking ① Fileinputformat reads data ② Mapper stage is simple for data processing ③ Serialization implements custom sorting ④ Partition partition processing ⑤ Reducer writes out data ⑥ Main class settings The specific implementation is as follows Driver main class, inclu ...

Danemu course Network website: www.tmooc.cn Account No.: qq email Password: the last four digits of ID card + the last four digits of mobile phone Computer function keys and shortcut keys functioninstructionsScreenshotPrtScQQ screenshotCTRL+ALT+ASelect allCTRL+AcopyCTRL+CpasteCTRL+VshearCTRL+XrevokeCTRL+ZAnti revocationCTRL+Ypreservation ...

Three components JobClient (prepare to run environment)JobTracker (receive job)TaskTracker (initialize job) Note that this is written in version 1.x and Hadoop 2. X and is managed by yarn. There are no JobTracker and TaskTracker Comparison between old and new Hadoop MapReduce frameworks 1. The client remains unchanged, and most of its call ...

4. Set set Set (also known as: Set) represents a set without duplicate elements. Features: unique, disordered The only meaning is that the elements in the Set are unique and there are no duplicate elementsUnordered means that the order in which the elements in the Set are added and taken out is inconsistent Format I: Create an empty immutabl ...

Construction of ecological environment of Hadoop 3 Apache platform System environment The server: hadoop0,hadoop1,hadoop2 Operating system: CentOS 7.6 Software list and version: - jdk-8u202-linux-x64 - hadoop-3.2.28. - zookeeper-3.4.10 - afka_2.12-2.7.11 - spark-3.1.2-bin-hadoop3.2 - MySQL-5.1.72-1.glibc23.x86_64.rpm-bundle - hba ...

1. Classes and objects Scala is a functional object-oriented language. It also supports the idea of object-oriented programming, and also has the concept of class and object. We can still develop object-oriented applications based on Scala. 1.1 related concepts What is object oriented? Object oriented is a programming idea, It is based on p ...

1. Introduction to characteristics 1.1 general Sometimes, we will encounter some specific needs, that is, to strengthen the functions of some classes (or objects) without affecting the current inheritance system. For example, there are monkeys and elephants. They all have names, ages and eating functions, but some monkeys are trained by the c ...

[software engineering practice] Hive research - Blog9 2021SC@SDUSC Research content introduction I am responsible for converting the query block QB into a logical query plan (OP Tree) The following code comes from apaceh-hive-3.1.2-src/ql/src/java/org/apache/hadoop/hive/ql/plan, which is my analysis object code. In the previous Hive research ...

Learning objectives: 1. Understand and master the logistic regression classification method; 2. Master the effect evaluation of logistic regression model; 3. Master the application scenarios of decision tree classification. Learning content: 1. This experiment is the analysis and prediction of telecom customer churn rate. 2. Analy ...