R version 3.4.3 (2017-11-30) -- "Kite-Eating Tree"

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Platform: x86_64-w64-mingw32/x64 (64-bit)

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> x<- 1

> x

[1] 1

> class(x)

[1] "numeric"

> x<- 3.14

> class(x)

[1] "numeric"

> x<- 2L

> X <- 5

> y <- "yes"

> class(y)

[1] "character"

> x <- vector("character", length = 10)

> x1 <- 1:4

> x2 <- c(1,2,3,4)

> x3 <- c(TRUE, 10, "a")

> as.numeric()

numeric(0)

> as.numeric(x)

 [1] NA NA NA NA NA NA NA NA NA NA

> x4 <- c("a","b","c")

> as.numeric(x)

 [1] NA NA NA NA NA NA NA NA NA NA

> x <- matrix(nrow = 3, ncol = 2)

> x <- matrix(1:6,nrow = 3, ncol = 2)

> l <- list("a",2,10L,3+4i,TRUE)