R 그룹별 건수 구하기

1 개요

R 그룹별 합 구하기

• 대략 "SELECT fruit, COUNT(ea) FROM df GROUP BY fruit"

df <- read.csv( header=T, stringsAsFactors=F, text="
day,fruit,ea
2019-06-01,apple,1
2019-06-11,apple,1
2019-06-21,banana,2
2019-07-01,apple,3
2019-07-11,banana,4
2019-08-25,orange,2
")
table(df$fruit)
##  apple banana orange 
##      3      2      1

library(sqldf)
sqldf("SELECT fruit, COUNT(ea) FROM df GROUP BY fruit")
##    fruit COUNT(ea)
## 1  apple         3
## 2 banana         2
## 3 orange         1

2 같이 보기

• R tapply()
• R aggregate()
• R 그룹별 건수 구하기
• SQL 그룹별 합 구하기

3 참고

• https://stackoverflow.com/questions/1660124/how-to-sum-a-variable-by-group