Book Image

Learning Pentaho Data Integration 8 CE - Third Edition

Book Image

Learning Pentaho Data Integration 8 CE - Third Edition

Overview of this book

Pentaho Data Integration(PDI) is an intuitive and graphical environment packed with drag-and-drop design and powerful Extract-Tranform-Load (ETL) capabilities. This book shows and explains the new interactive features of Spoon, the revamped look and feel, and the newest features of the tool including transformations and jobs Executors and the invaluable Metadata Injection capability. We begin with the installation of PDI software and then move on to cover all the key PDI concepts. Each of the chapter introduces new features, enabling you to gradually get practicing with the tool. First, you will learn to do all kind of data manipulation and work with simple plain files. Then, the book teaches you how you can work with relational databases inside PDI. Moreover, you will be given a primer on data warehouse concepts and you will learn how to load data in a data warehouse. During the course of this book, you will be familiarized with its intuitive, graphical and drag-and-drop design environment. By the end of this book, you will learn everything you need to know in order to meet your data manipulation requirements. Besides, your will be given best practices and advises for designing and deploying your projects.
Table of Contents (17 chapters)

Filtering data


By now, you have learned how to do several kinds of calculations which enrich the set of data. There is still another kind of operation that is frequently used; it does not have to do with enriching the data but with discarding or filtering unwanted information. That's the core of this section.

Filtering rows upon conditions

Suppose you have a dataset and you only want to keep the rows that match a condition. To demonstrate how to implement this kind of filtering, we will read a file, build a list of words found in the file, and then filter the nulls or unwanted words. We will split the exercise into two parts:

  • In the first part, we will read the file and prepare the data for filtering
  • In the second part, we will effectively filter the data

Reading a file and getting the list of words found in it

Let's start by reading a sample file.

Note

Before starting, you'll need at least one text file to play with. The text file used in this tutorial is named smcng10.txt. Its content is about...