R 기본 문법 연습 3

R 기본 문법 연습

d <- matrix(1:9, ncol=3)
d
apply(d, 1, sum)
apply(d, 2, sum)
head(iris)
apply(iris[,1:4], 2, sum)
colSums(iris[,1:4])
​
result <- lapply(1:3, function(x) { x*2 })
result
unlist(result)
​
x<-list(a=1:3, b=4:6)
x
x$a
x$b
lapply(x, mean)
lapply(iris[,1:4], mean)
colMeans(iris[,1:4])
d<-as.data.frame(matrix(unlist(lapply(iris[,1:4], mean)),ncol=4,byrow=T)) 
names(d) <- names(iris[,1:4])
d
​
a<-lapply(iris[,1:4], mean)
a
b<-sapply(iris[,1:4], mean)
b
class(b)
c<-as.data.frame(b)
c
c<-as.data.frame(t(b))
c
e<-tapply(1:10, rep(1,10), sum)
e
1:10 %% 2 == 1
f<-tapply(1:10, 1:10 %% 2 ==1, sum)
f
tapply(iris$Sepal.Length, iris$Species, mean)
​
m<-matrix(1:8, ncol=2, dimnames=list(c("spring", "summer", "fall", "winter"),
                                    c("male", "female")))
m
list(c(1,1,2,2,1,1,2,2), c(1,1,1,1,2,2,2,2))
tapply(m, list(c(1,1,2,2,1,1,2,2), c(1,1,1,1,2,2,2,2)), sum)
​
install.packages("sqldf")
library(sqldf)
a<-sqldf("select distinct Species from iris")
a
b<-data.frame(sqldf("select * from iris where Species='setosa'"))
b
sqldf('select avg("sepal.length") from iris where Species ="setosa"')
mean(subset(iris, Species == "setosa")$Sepal.Length)
sqldf('select * from iris where "sepal.length" > 5.0')
sqldf('select species, avg("sepal.length") from iris group by species')
sapply(split(iris$Sepal.Length, iris$Species), mean)
​
​

R Studio 로 확인하면서 기본적인 문법을 공부할수있다.