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Learning PySpark

Learning PySpark

By : Drabas, Lee
3.9 (194)
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Learning PySpark

Learning PySpark

3.9 (194)
By: Drabas, Lee

Overview of this book

Apache Spark is an open source framework for efficient cluster computing with a strong interface for data parallelism and fault tolerance. This book will show you how to leverage the power of Python and put it to use in the Spark ecosystem. You will start by getting a firm understanding of the Spark 2.0 architecture and how to set up a Python environment for Spark. You will get familiar with the modules available in PySpark. You will learn how to abstract data with RDDs and DataFrames and understand the streaming capabilities of PySpark. Also, you will get a thorough overview of machine learning capabilities of PySpark using ML and MLlib, graph processing using GraphFrames, and polyglot persistence using Blaze. Finally, you will learn how to deploy your applications to the cloud using the spark-submit command. By the end of this book, you will have established a firm understanding of the Spark Python API and how it can be used to build data-intensive applications.
Table of Contents (13 chapters)
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12
Index

Checking for duplicates, missing observations, and outliers


Until you have fully tested the data and proven it worthy of your time, you should neither trust it nor use it. In this section, we will show you how to deal with duplicates, missing observations, and outliers.

Duplicates

Duplicates are observations that appear as distinct rows in your dataset, but which, upon closer inspection, look the same. That is, if you looked at them side by side, all the features in these two (or more) rows would have exactly the same values.

On the other hand, if your data has some form of an ID to distinguish between records (or associate them with certain users, for example), then what might initially appear as a duplicate may not be; sometimes systems fail and produce erroneous IDs. In such a situation, you need to either check whether the same ID is a real duplicate, or you need to come up with a new ID system.

Consider the following example:

df = spark.createDataFrame([
        (1, 144.5, 5.9, 33, 'M')...

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