课程

Joining Data with data.table in R

中级技能水平

更新时间 2024年8月

This course will show you how to combine and merge datasets with data.table.

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RData Manipulation

4小时

13 视频

47 道练习

3,950 XP

17,316

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课程描述

In the real world, data sets typically come split across many tables while most data analysis functions in R are designed to work with single tables of data. In this course, you'll learn how to effectively combine data sets into single tables using data.table. You'll learn how to add columns from one table to another table, how to filter a table based on observations in another table, and how to identify records across multiple tables matching complex criteria. Along the way, you'll learn how to troubleshoot failed join operations and best practices for working with complex data sets. After completing this course you'll be well on your way to be a data.table master!

先决条件

Data Manipulation with data.table in R

1

Joining Multiple data.tables

This chapter will show you how to perform simple joins that will enable you to combine information spread across multiple tables.

Welcome to the course

Exploring data.tables

Identifying join keys

Multiple data.tables, multiple keys

The merge function

Left and right joins

Mastering simple joins

2

Joins Using data.table Syntax

In this chapter you will perform joins using the data.table syntax, set and view data.table keys, and perform anti-joins.

Joins using data.table syntax

Right join with the data.table syntax

Inner join with the data.table syntax

Setting and viewing data.table keys

Setting keys

Getting keys

Incorporating joins into your data.table workflow

Exploring the Australian population

Finding multiple matches

Exploring world life expectancy

3

Diagnosing and Fixing Common Join Problems

This chapter will discuss common problems and errors encountered when performing data.table joins and show you how to troubleshoot and avoid them.

Complex keys

Keys with different names

Multi-column keys

Multi-key, single-key

Tricky columns

Column name suffixes

Joining a data.frame

Duplicate matches

Joining with missing values

Filtering duplicates

Joining and filtering duplicates

4

Concatenating and Reshaping data.tables

In the last chapter of this course you'll learn how to concatenate observations from multiple tables together, how to identify observations present in one table but not another, and how to reshape tables between long and wide formats.

Concatenating two or more data.tables

Concatenating data.table variables

Concatenating a list of data.tables

Set operations

Identifying observations shared by multiple tables

Removing duplicates while combining tables

Identifying observations unique to a table

Melting data.tables

Melting a wide table

Casting data.tables

Casting a long table

Casting multiple columns

Splitting by multiple groups

Joining Data with data.table in R

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