#결측값 대치 방법 - 완전분석법
copy_iris <- iris
dim (copy_iris)
copy_iris[sample(1:150,30), 1] <- NA
copy_iris <- copy_iris[complete.cases(copy_iris), ]
dim(copy_iris)

#결측값 대치 방법 - 평균대치법
copy_iris <- iris
copy_iris[sample(1:150,30), 1] <- NA
meanValue <- mean(copy_iris$Sepal.Length , na.rm=T)
copy_iris$Sepal.Length[is.na(copy_iris$Sepal.Length)] <- meanValue
library(mice)
copy_iris[sample(1:150,30), 1] <- NA
copy_iris <- complete(mice(copy_iris, m=1, method="mean", seed=123))

#결측값 대치 방법 - 단순확률대치법
copy_iris <- iris
copy_iris[sample(1:150,30), 1] <- NA
library(VIM)
copy_iris <- kNM(copy_iris, k = 10)[ , c(1:5)]

#결측값 대치 방법 - 다중대치법
copy_iris <- iris
copy_iris[sample(1:150,30), 1] <- NA
library(Amelia)
iris_imp <- amelia(copy_iris, m = 3, cs = "Species")
copy_iris$Sepal.Length <- iris_imp$imputations[[3]]$Sepal.Length