R for DS_03 ggplot2

Welcome

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• 저작권 : “R for DataScience by Hadley Wickham and Garrett Grolemund(O’Reilly). Copyright 2017 Garrett Grolemund, Hadley Wickham, 978-1-491-91039-9

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Introduction

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• how to visualise your data using ggplot2. R
• ggplot2는 그래프를 그려주는 프로그램
  ggplot2 이론배경

3.1.1 Prerequisites

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install.packages("tidyverse")

library(tidyverse)
#> ── Attaching packages ─────────────────────────────────────── tidyverse 1.3.0 ──
#> ✔ ggplot2 3.3.2     ✔ purrr   0.3.4
#> ✔ tibble  3.0.3     ✔ dplyr   1.0.2
#> ✔ tidyr   1.1.2     ✔ stringr 1.4.0
#> ✔ readr   1.4.0     ✔ forcats 0.5.0
#> ── Conflicts ────────────────────────────────────────── tidyverse_conflicts() ──
#> ✖ dplyr::filter() masks stats::filter()
#> ✖ dplyr::lag()    masks stats::lag()

install.packages(c("nycflights13", "gapminder", "Lahman"))

3.2 First steps

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3.2.1 The mpg data frame

• US Environmental Protection Agency on 38 models of car
• A data frame is a rectangular

mpg

• displ = car’s engine size, in litres
• hwy = fuel efficiency in miles per gallon (mpg)

3.2.2 Creating a ggplot

ggplot(data = mpg) +
  geom_point(mapping = aes(x= displ, y = hwy))

• ggplot(data = mpg) : 비어있는 Graph를 만들어 준다.
• geom_point() : Layers 추가
• scatterplot

• mapping = aes(x= displ, y = hwy) : x와 y를 mapping 해 준다.

3.2.3 A graphing template

ggplot(data = <DATA>) + 
  <GEOM_FUNCTION>(mapping = aes(<MAPPINGS>))

이런 식으로 쓰면 된다고 함. (모형)

3.3 Aesthetic mappings

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aesthetic : 래전드 모양, 색 크기

• value : data
• level : aesthetic properties
• size : 크기
• color = colour, aesthetic의 색
• alpha = shape , aesthetic의 모양

ggplot(data = mpg) +
  geom_point(mapping = aes(x = displ, y = hwy, color = class))

ggplot(data = mpg) +
  geom_point(mapping = aes(x = displ, y = hwy, size = class))

colour , color : 모두 써도 됨.

ggplot(data = mpg) +
  geom_point(mapping = aes(x = displ, y= hwy, alpha = class))

ggplot(data = mpg) +
  geom_point(mapping = aes(x = displ, y = hwy, shape = class))

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(수동으로 색 설정)

래전드를 생성 하지 않으면서 color만 바꿀 수 있다.

ggplot(data = mpg) + 
  geom_point(mapping = aes(x = displ, y = hwy), color = "blue")

ggplot(data = mpg) + 
  geom_point(mapping = aes(x = displ, y = hwy, color = "blue"))

mpg 내의 data가 color이라는 column이 있다.

그 data가 “blue”인 data들의 displ과 hwy의 Graph

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아직 덜 했다 !

rmarkdown_Book

R publishing

Rggplot