Lesson 14: ggplot2

Author

최규빈

Published

July 26, 2023

강의영상

import numpy as np
import pandas as pd 
from plotnine import *

read mpg data

- ref: https://r4ds.had.co.nz/index.html

df = pd.read_csv('https://raw.githubusercontent.com/guebin/DV2022/master/posts/mpg.csv')
df

	manufacturer	model	displ	year	cyl	trans	drv	cty	hwy	fl	class
0	audi	a4	1.8	1999	4	auto(l5)	f	18	29	p	compact
1	audi	a4	1.8	1999	4	manual(m5)	f	21	29	p	compact
2	audi	a4	2.0	2008	4	manual(m6)	f	20	31	p	compact
3	audi	a4	2.0	2008	4	auto(av)	f	21	30	p	compact
4	audi	a4	2.8	1999	6	auto(l5)	f	16	26	p	compact
...	...	...	...	...	...	...	...	...	...	...	...
229	volkswagen	passat	2.0	2008	4	auto(s6)	f	19	28	p	midsize
230	volkswagen	passat	2.0	2008	4	manual(m6)	f	21	29	p	midsize
231	volkswagen	passat	2.8	1999	6	auto(l5)	f	16	26	p	midsize
232	volkswagen	passat	2.8	1999	6	manual(m5)	f	18	26	p	midsize
233	volkswagen	passat	3.6	2008	6	auto(s6)	f	17	26	p	midsize

234 rows × 11 columns

- 깃허브 저장소에 아예 데이터만 따로 모아서 관리하는 것도 좋은 방법입니다.

data 설명

- displ: 자동차의 엔진크기

- hwy: 연료의 효율, 동일한 연료로 얼마나 멀리 가느냐?

p9를 이용한 산점도 (2차원)

python에서: plotnine을 이용한 산점도

df.head(n=3)

	manufacturer	model	displ	year	cyl	trans	drv	cty	hwy	fl	class
0	audi	a4	1.8	1999	4	auto(l5)	f	18	29	p	compact
1	audi	a4	1.8	1999	4	manual(m5)	f	21	29	p	compact
2	audi	a4	2.0	2008	4	manual(m6)	f	20	31	p	compact

ggplot(data=df)\
+ geom_point(
    mapping=aes(x='displ',y='hwy')
) ## plotnine

<Figure Size: (640 x 480)>

산점도 해석: 엔진크기가 클수록 효율이 낮음.

- 빠르게 그리기: data=와 mapping=은 생략가능함

ggplot(df)\
+ geom_point(
    aes(x='displ',y='hwy')
)

<Figure Size: (640 x 480)>

객체지향적인 느낌으로 산점도 그리기

step1: 도화지를 준비한다.

fig = ggplot(data=df)
fig

<Figure Size: (640 x 480)>

step2 변수와 에스테틱사이의 맵핑을 설정한다.

a1= aes(x='displ',y='hwy')
a1

{'x': 'displ', 'y': 'hwy'}

step3 점들의 집합을 만든다. 즉 포인트 지옴을 만든다.

point1=geom_point(mapping=a1)

geom_point(): 점들을 그려! 어떻게?
a1에서 설정된 표를 보고

step4 도화지와 지옴을 합친다.

fig+point1

<Figure Size: (640 x 480)>

p9를 이용한 산점도 (3차원)

- 데이터를 다시 관찰

df.head()

	manufacturer	model	displ	year	cyl	trans	drv	cty	hwy	fl	class
0	audi	a4	1.8	1999	4	auto(l5)	f	18	29	p	compact
1	audi	a4	1.8	1999	4	manual(m5)	f	21	29	p	compact
2	audi	a4	2.0	2008	4	manual(m6)	f	20	31	p	compact
3	audi	a4	2.0	2008	4	auto(av)	f	21	30	p	compact
4	audi	a4	2.8	1999	6	auto(l5)	f	16	26	p	compact

- class도 함께 plot에 표시하면 데이터를 탐색할때 좀 더 좋을 것 같다.

산점도 + 점크기변경

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

/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/scales/scale_size.py:49: PlotnineWarning: Using size for a discrete variable is not advised.

<Figure Size: (640 x 480)>

산점도 + 투명도변경

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

/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/scales/scale_alpha.py:73: PlotnineWarning: Using alpha for a discrete variable is not advised.

<Figure Size: (640 x 480)>

산점도 + 투명도/점크기를 동시에 적용

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

/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/scales/scale_alpha.py:73: PlotnineWarning: Using alpha for a discrete variable is not advised.
/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/scales/scale_size.py:49: PlotnineWarning: Using size for a discrete variable is not advised.

<Figure Size: (640 x 480)>

산점도 + 형태

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

<Figure Size: (640 x 480)>

산점도 + 색깔

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

<Figure Size: (640 x 480)>

객체지향적 느낌으로?

a2 = aes(x='displ', y='hwy', color='class')

a1,a2

({'x': 'displ', 'y': 'hwy'}, {'x': 'displ', 'y': 'hwy', 'color': 'class'})

point2=geom_point(a2)

fig+point2

<Figure Size: (640 x 480)>

산점도 + 색깔 + 적합선

- 일단 색깔이 없는 포인트 지옴부터 연습

fig+point1

<Figure Size: (640 x 480)>

line1 = geom_smooth(a1)

fig+point1+line1

/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/stats/smoothers.py:330: PlotnineWarning: Confidence intervals are not yet implemented for lowess smoothings.

<Figure Size: (640 x 480)>

- point1(색깔없는 포인트 지옴)을 point2(색깔있는 포인트 지옴)으로 언제든지 바꿔치기 가능!

fig+point2+line1

/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/stats/smoothers.py:330: PlotnineWarning: Confidence intervals are not yet implemented for lowess smoothings.

<Figure Size: (640 x 480)>

- 명령어로 한번에 그리기

ggplot(data=df) + \
geom_point(mapping=aes(x='displ',y='hwy',color='class')) + \
geom_smooth(mapping=aes(x='displ',y='hwy'))

/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/stats/smoothers.py:330: PlotnineWarning: Confidence intervals are not yet implemented for lowess smoothings.

<Figure Size: (640 x 480)>

- 공통적인 맵핑규칙은 ggplot()쪽으로 빼기도 한다. (figure를 선언하는 곳에서 공통으로 선언함)

ggplot(data=df,mapping=aes(x='displ',y='hwy')) + \
geom_point(mapping=aes(color='class')) + \
geom_smooth()

/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/stats/smoothers.py:330: PlotnineWarning: Confidence intervals are not yet implemented for lowess smoothings.

<Figure Size: (640 x 480)>

p9를 이용한 산점도 (4차원)

- 데이터를 살펴보자.

df.head()

	manufacturer	model	displ	year	cyl	trans	drv	cty	hwy	fl	class
0	audi	a4	1.8	1999	4	auto(l5)	f	18	29	p	compact
1	audi	a4	1.8	1999	4	manual(m5)	f	21	29	p	compact
2	audi	a4	2.0	2008	4	manual(m6)	f	20	31	p	compact
3	audi	a4	2.0	2008	4	auto(av)	f	21	30	p	compact
4	audi	a4	2.8	1999	6	auto(l5)	f	16	26	p	compact

산점도 + 점크기변경 + 색깔

- drv (전륜, 후륜, 4륜 구동)에 따라서 데이터를 시각화 하고 싶다.

ggplot(data=df, mapping=aes(x='displ',y='hwy'))\
+ geom_point(mapping=aes(
    size='class',
    color='drv'
),alpha=0.3)

/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/scales/scale_size.py:49: PlotnineWarning: Using size for a discrete variable is not advised.

<Figure Size: (640 x 480)>

모든 \(x\)에 대하여 붉은색 점들이 대부분 초록색과 보라색 점들에 비하여 아래쪽에 있음 \(\to\) 4륜구동방식이 연비가 좋지 않음

산점도 + 점크기변경 + 색깔 (객체지향버전)

- 맵핑규칙

a1,a2

({'x': 'displ', 'y': 'hwy'}, {'x': 'displ', 'y': 'hwy', 'color': 'class'})

a3 = a2.copy()

a2,a3

({'x': 'displ', 'y': 'hwy', 'color': 'class'},
 {'x': 'displ', 'y': 'hwy', 'color': 'class'})

a3['color'] = 'drv'
a3['size'] = 'class'
a3

{'x': 'displ', 'y': 'hwy', 'color': 'drv', 'size': 'class'}

아래와 같이 선언해도 괜찮음

a3= aes(x='displ',y='hwy',color='drv',size='class')

point3=geom_point(a3)

fig+point3

/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/scales/scale_size.py:49: PlotnineWarning: Using size for a discrete variable is not advised.

<Figure Size: (640 x 480)>

그림의 전체적인 투명도를 조절하면 좋겠음

point3=geom_point(a3,alpha=0.2)
fig+point3

/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/scales/scale_size.py:49: PlotnineWarning: Using size for a discrete variable is not advised.

<Figure Size: (640 x 480)>

산점도 + 점크기변경 + 색깔 + 선추가

fig+point3+line1

/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/scales/scale_size.py:49: PlotnineWarning: Using size for a discrete variable is not advised.
/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/stats/smoothers.py:330: PlotnineWarning: Confidence intervals are not yet implemented for lowess smoothings.

<Figure Size: (640 x 480)>

산점도 + 점크기변경 + 색깔 + drv별로 선추가

- 맵핑규칙

a1,a2,a3

({'x': 'displ', 'y': 'hwy'},
 {'x': 'displ', 'y': 'hwy', 'color': 'class'},
 {'x': 'displ', 'y': 'hwy', 'color': 'drv', 'size': 'class'})

a4 = a2.copy() 
a4['color']='drv'
a4

{'x': 'displ', 'y': 'hwy', 'color': 'drv'}

line2 = geom_smooth(a4)

fig + point3 + line2

/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/scales/scale_size.py:49: PlotnineWarning: Using size for a discrete variable is not advised.
/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/stats/smoothers.py:330: PlotnineWarning: Confidence intervals are not yet implemented for lowess smoothings.
/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/stats/smoothers.py:330: PlotnineWarning: Confidence intervals are not yet implemented for lowess smoothings.
/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/stats/smoothers.py:330: PlotnineWarning: Confidence intervals are not yet implemented for lowess smoothings.

<Figure Size: (640 x 480)>

- 선의 색깔을 동일하게 하고 선의 타입을 변경하여 drv를 표시하고 싶다면?

a1,a2,a3,a4

({'x': 'displ', 'y': 'hwy'},
 {'x': 'displ', 'y': 'hwy', 'color': 'class'},
 {'x': 'displ', 'y': 'hwy', 'color': 'drv', 'size': 'class'},
 {'x': 'displ', 'y': 'hwy', 'color': 'drv'})

a5=a1.copy()
a5['linetype']='drv' 
a5

{'x': 'displ', 'y': 'hwy', 'linetype': 'drv'}

line3 = geom_smooth(a5,size=0.5,color='gray')

fig+point3+line3

/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/scales/scale_size.py:49: PlotnineWarning: Using size for a discrete variable is not advised.
/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/stats/smoothers.py:330: PlotnineWarning: Confidence intervals are not yet implemented for lowess smoothings.
/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/stats/smoothers.py:330: PlotnineWarning: Confidence intervals are not yet implemented for lowess smoothings.
/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/stats/smoothers.py:330: PlotnineWarning: Confidence intervals are not yet implemented for lowess smoothings.

<Figure Size: (640 x 480)>

- 전체적인 추세선도 추가하고 싶다면?

fig+point3+line2+line1

/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/scales/scale_size.py:49: PlotnineWarning: Using size for a discrete variable is not advised.
/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/stats/smoothers.py:330: PlotnineWarning: Confidence intervals are not yet implemented for lowess smoothings.
/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/stats/smoothers.py:330: PlotnineWarning: Confidence intervals are not yet implemented for lowess smoothings.
/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/stats/smoothers.py:330: PlotnineWarning: Confidence intervals are not yet implemented for lowess smoothings.
/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/stats/smoothers.py:330: PlotnineWarning: Confidence intervals are not yet implemented for lowess smoothings.

<Figure Size: (640 x 480)>

- 그려보니까 역시 drv별로 그려지는 추세선은 색깔별로 구분하는게 좋겠음.

line2 = geom_smooth(a4,size=0.5,linetype='dashed')
fig+point3+line2+line1

/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/scales/scale_size.py:49: PlotnineWarning: Using size for a discrete variable is not advised.
/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/stats/smoothers.py:330: PlotnineWarning: Confidence intervals are not yet implemented for lowess smoothings.
/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/stats/smoothers.py:330: PlotnineWarning: Confidence intervals are not yet implemented for lowess smoothings.
/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/stats/smoothers.py:330: PlotnineWarning: Confidence intervals are not yet implemented for lowess smoothings.
/home/cgb2/anaconda3/envs/py310/lib/python3.10/site-packages/plotnine/stats/smoothers.py:330: PlotnineWarning: Confidence intervals are not yet implemented for lowess smoothings.

<Figure Size: (640 x 480)>

- 고차원을 변수를 표현할 수 있는 무기는 다양하다.

산점도(포인트지옴): 점의크기, 점의형태, 점의색깔, 점의투명도
라인플랏(스무스지옴,라인지옴): 선의형태, 선의색깔, 선의굵기

결론

- 잘 훈련한다면 여러가지 형태의 고차원 그래프를 우리도 그릴 수 있다. (마치 미나드처럼)

- 해들리위컴은 이러한 방법을 체계적으로 정리했다고 보여진다.

- 해들리위컴: 그래프는 데이터 + 지옴 + 맵핑(변수와 에스테틱간의 연결) + 스탯(통계) + 포지션 + 축 + 패싯그리드 7개의 조합으로 그릴 수 있다.

내생각: 지옴과 맵핑만 잘 다루어도 아주 다양한 그래프를 그릴 수 있음.