Data Visualization

dplyr Basics

Overview

Teaching: 10 min
Exercises: 5 min
Questions

  • What are the basic dplyr functions?

  • How do I implement the basic dplyr functions?

Objectives

  • To understand the basic dplyr functions: select(), filter(), group_by(), and summarize()

library(dplyr)

dplyr Challenge

How many countries are in Africa?

A. 5 B. 38 C. 52 D. 142

Answer

C. 52

Code Solution

Africa <- filter(data, continent=="Africa")
summarize(Africa, countries = n())

Make a data.frame that stores the count of countries per continent?

Output Solution

Source: local data frame [5 x 2]

  continent countries
     (fctr)     (int)
1    Africa        52
2  Americas        25
3      Asia        33
4    Europe        30
5   Oceania         2

Code Solution

data %>%
  group_by(continent) %>%
  summarize(countries = n())

Key Points