- Pig Design Patterns
- Pradeep Pasupuleti
- 208字
- 2021-07-16 12:07:57
Conventions
In this book, you will find a number of styles of text that distinguish between different kinds of information. Here are a few examples of these styles and an explanation of their meaning.
Code words in text are shown as follows: "From this point onward, we shall call the unpacked Hadoop directory HADOOP_HOME."
A block of code for UDFs written in Java is set as follows:
package com.pigdesignpatterns.myudfs;
public class DeIdentifyUDF extends EvalFunc<String> {
@Override
public String exec(Tuple input){
try {
String plainText = (String)input.get(0);
String encryptKey = (String)input.get(1);
String str="";
str = encrypt(plainText,encryptKey.getBytes());
return str;
}
catch (NullPointerException npe) {
warn(npe.toString(), PigWarning.UDF_WARNING_2);
return null;
} catch (StringIndexOutOfBoundsException npe) {
warn(npe.toString(), PigWarning.UDF_WARNING_3);
return null;
} catch (ClassCastException e) {
warn(e.toString(), PigWarning.UDF_WARNING_4);
return null;
}
Pig Script is displayed as follows:
Users = load 'users' as (name, age); Fltrd = filter Users by age >= 18 and age <= 25; Pages = load 'pages' as (user, url); Jnd = join Fltrd by name, Pages by user; Grpd = group Jnd by url; Smmd = foreach Grpd generate group, COUNT(Jnd) as clicks; Srtd = order Smmd by clicks desc; Top5 = limit Srtd 5; store Top5 into 'top5sites'
Any command-line input or output is written as follows:
>tar -zxvf hadoop-1.x.x.tar.gz
New terms and important words are shown in bold. Words that you see on the screen, in menus or dialog boxes for example, appear in the text like this: "Clicking the Next button moves you to the next screen."