Book Image

Clojure Data Analysis Cookbook

By : Eric Rochester
Book Image

Clojure Data Analysis Cookbook

By: Eric Rochester

Overview of this book

<p>Data is everywhere and it's increasingly important to be able to gain insights that we can act on. Using Clojure for data analysis and collection, this book will show you how to gain fresh insights and perspectives from your data with an essential collection of practical, structured recipes.<br /><br />"The Clojure Data Analysis Cookbook" presents recipes for every stage of the data analysis process. Whether scraping data off a web page, performing data mining, or creating graphs for the web, this book has something for the task at hand.<br /><br />You'll learn how to acquire data, clean it up, and transform it into useful graphs which can then be analyzed and published to the Internet. Coverage includes advanced topics like processing data concurrently, applying powerful statistical techniques like Bayesian modelling, and even data mining algorithms such as K-means clustering, neural networks, and association rules.</p>
Table of Contents (18 chapters)
Clojure Data Analysis Cookbook
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Grouping data with $group-by


Datasets often come with inherent structure. Two or more rows may have the same value in one column, and we may want to leverage that by grouping those rows together in our analysis.

Getting ready

First, we'll need to declare a dependency on Incanter in the project.clj file:

:dependencies [[org.clojure/clojure "1.4.0"]
               [incanter "1.4.1"]]

Next, we'll include Incanter core and io in our script or REPL.

(use '(incanter core io))

For data, we'll use the census race data for all states. We first saw this in the Selecting columns with $ recipe, and we can download it from http://www.ericrochester.com/clj-data-analysis/data/all_160.P3.csv.

(def data-file "data/all_160.P3.csv")
(def race-data (read-dataset data-file :header true))

How to do it…

Incanter lets us group rows for further analysis or summarizing with the $group-by function. All we need to do is pass the data to $group-by with the column or function to group on.

(def by-state ($group-by :STATE race...