R merge()

1 개요

R merge()

• 특정 컬럼(들)을 기준으로 컬럼들을 병합하는 R 함수
• SQL의 JOIN과 유사하다.

all 옵션	SQL JOIN
all=FALSE (기본값)	INNER JOIN
all=TRUE	FULL OUTER JOIN
all.x=TRUE	LEFT JOIN
all.y=TRUE	RIGHT JOIN

majors <- read.table( header=TRUE, stringsAsFactors=FALSE, text="
Name    Major
Alice   Art
Bob     Biology
Dave    Dance
Eve     English
")
majors
##    Name   Major
## 1 Alice     Art
## 2   Bob Biology
## 3  Dave   Dance
## 4   Eve English

grades <- read.table( header=TRUE, stringsAsFactors=FALSE, text="
Name    Grade
Alice   A
Bob     B
Carol   C
")
grades
##    Name Grade
## 1 Alice     A
## 2   Bob     B
## 3 Carol     C

merge(x=majors, y=grades, id='Name')
##    Name   Major Grade
## 1 Alice     Art     A
## 2   Bob Biology     B

merge(x=majors, y=grades, id='Name', all=TRUE)
##    Name   Major Grade
## 1 Alice     Art     A
## 2   Bob Biology     B
## 3 Carol    <NA>     C
## 4  Dave   Dance  <NA>
## 5   Eve English  <NA>

merge(x=majors, y=grades, id='Name', all.x=TRUE)
##    Name   Major Grade
## 1 Alice     Art     A
## 2   Bob Biology     B
## 3  Dave   Dance  <NA>
## 4   Eve English  <NA>

merge(x=majors, y=grades, id='Name', all.y=TRUE)
##    Name   Major Grade
## 1 Alice     Art     A
## 2   Bob Biology     B
## 3 Carol    <NA>     C

2 같이 보기

• R data.frame()
• R by()
• R cbind()
• R dendrogram

3 참고

• https://www.rdocumentation.org/packages/base/versions/3.5.3/topics/merge