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
")
grades <- read.table( header=TRUE, stringsAsFactors=FALSE, text="
Name Grade
Alice A
Bob B
Carol C
")
merge(x=majors, y=grades, id='Name')
merge(x=majors, y=grades, id='Name', all=TRUE)
merge(x=majors, y=grades, id='Name', all.x=TRUE)
merge(x=majors, y=grades, id='Name', all.y=TRUE)