R 그룹별 합 구하기

1 개요

R 그룹별 합 구하기

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

R

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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
")
df

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2 방법 1: aggregate ★

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aggregate(ea ~ fruit, df, sum)

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3 방법 2: tapply

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tapply(df$ea, df$fruit, sum)

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4 방법 3: sqldf

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library(sqldf)
sqldf("SELECT fruit, SUM(ea) AS s FROM df GROUP BY fruit")

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5 같이 보기

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

6 참고

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