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R Machine Learning By Example

You're reading from   R Machine Learning By Example Understand the fundamentals of machine learning with R and build your own dynamic algorithms to tackle complicated real-world problems successfully

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Product type Paperback
Published in Mar 2016
Publisher
ISBN-13 9781784390846
Length 340 pages
Edition 1st Edition
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Author (1):
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Raghav Bali Raghav Bali
Author Profile Icon Raghav Bali
Raghav Bali
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Table of Contents (10) Chapters Close

Preface 1. Getting Started with R and Machine Learning FREE CHAPTER 2. Let's Help Machines Learn 3. Predicting Customer Shopping Trends with Market Basket Analysis 4. Building a Product Recommendation System 5. Credit Risk Detection and Prediction – Descriptive Analytics 6. Credit Risk Detection and Prediction – Predictive Analytics 7. Social Media Analysis – Analyzing Twitter Data 8. Sentiment Analysis of Twitter Data Index

Data preprocessing


In this section, we will be focusing on data preprocessing which includes data cleaning, transformation, and normalizations if required. Basically, we perform operations to get the data ready before we start performing any analysis on it.

Dealing with missing values

There will be situations when the data you are dealing with will have missing values, which are often represented as NA in R. There are several ways to detect them and we will show you a couple of ways next. Note that there are several ways in which you can do this.

> # check if data frame contains NA values
> sum(is.na(credit.df))
[1] 0
> 
> # check if total records reduced after removing rows with NA 
> # values
> sum(complete.cases(credit.df))
[1] 1000

The is.na function is really useful as it helps in finding out if any element has an NA value in the dataset. There is another way of doing the same by using the complete.cases function, which essentially returns a logical vector saying whether...

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