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You're reading from  R for Data Science Cookbook (n)

Product typeBook
Published inJul 2016
Reading LevelIntermediate
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ISBN-139781784390815
Edition1st Edition
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Author (1)
Yu-Wei, Chiu (David Chiu)
Yu-Wei, Chiu (David Chiu)
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Yu-Wei, Chiu (David Chiu)

Yu-Wei, Chiu (David Chiu) is the founder of LargitData (www.LargitData.com), a startup company that mainly focuses on providing big data and machine learning products. He has previously worked for Trend Micro as a software engineer, where he was responsible for building big data platforms for business intelligence and customer relationship management systems. In addition to being a start-up entrepreneur and data scientist, he specializes in using Spark and Hadoop to process big data and apply data mining techniques for data analysis. Yu-Wei is also a professional lecturer and has delivered lectures on big data and machine learning in R and Python, and given tech talks at a variety of conferences. In 2015, Yu-Wei wrote Machine Learning with R Cookbook, Packt Publishing. In 2013, Yu-Wei reviewed Bioinformatics with R Cookbook, Packt Publishing. For more information, please visit his personal website at www.ywchiu.com. **********************************Acknowledgement************************************** I have immense gratitude for my family and friends for supporting and encouraging me to complete this book. I would like to sincerely thank my mother, Ming-Yang Huang (Miranda Huang); my mentor, Man-Kwan Shan; the proofreader of this book, Brendan Fisher; Members of LargitData; Data Science Program (DSP); and other friends who have offered their support.
Read more about Yu-Wei, Chiu (David Chiu)

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Merging large datasets with a data.table


In previous recipes, we demonstrated how to manipulate and aggregate data with a data.table. In addition to performing data manipulation on a single table, we often need to import additional features or correlate data from other data sources. Therefore, we can join two or more tables into one. In this recipe, we introduce some methods that we can use to merge two data.table.

Getting ready

Ensure that you completed the Enhancing a data.frame with a data.table recipe to load purchase_view.tab and purchase_order.tab as both data.frame and data.table into your R environment.

How to do it…

Perform the following steps to merge two data.table:

  1. First, we generate a product.dt data table by calculating the number of purchased items:

    > product.dt <- order.dt[,.(Buy = length(Action)),by=Product]
    > head(product.dt[order(-Buy)])
              Product Buy
    1:    P0005772981 821
    2:    P0024239865 729
    3:    P0004607050 584
    4:    P0003425855 552
    5:    P0014252066 438...
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R for Data Science Cookbook (n)
Published in: Jul 2016Publisher: ISBN-13: 9781784390815

Author (1)

author image
Yu-Wei, Chiu (David Chiu)

Yu-Wei, Chiu (David Chiu) is the founder of LargitData (www.LargitData.com), a startup company that mainly focuses on providing big data and machine learning products. He has previously worked for Trend Micro as a software engineer, where he was responsible for building big data platforms for business intelligence and customer relationship management systems. In addition to being a start-up entrepreneur and data scientist, he specializes in using Spark and Hadoop to process big data and apply data mining techniques for data analysis. Yu-Wei is also a professional lecturer and has delivered lectures on big data and machine learning in R and Python, and given tech talks at a variety of conferences. In 2015, Yu-Wei wrote Machine Learning with R Cookbook, Packt Publishing. In 2013, Yu-Wei reviewed Bioinformatics with R Cookbook, Packt Publishing. For more information, please visit his personal website at www.ywchiu.com. **********************************Acknowledgement************************************** I have immense gratitude for my family and friends for supporting and encouraging me to complete this book. I would like to sincerely thank my mother, Ming-Yang Huang (Miranda Huang); my mentor, Man-Kwan Shan; the proofreader of this book, Brendan Fisher; Members of LargitData; Data Science Program (DSP); and other friends who have offered their support.
Read more about Yu-Wei, Chiu (David Chiu)