## Objects

x <- rnorm(30)

y <- x[x>0]

z <- x
z[z<0] <- 0

m <- matrix(x, nrow = 5)
str(m)

d.f <- as.data.frame(m)
str(d.f)

m[2,2] = "a"
d.f[2,2] = "a"
str(m)
str(d.f)


## Basic I/O and filehandling
# Binary files

save(m, file="my.file.with.m.R")

rm(m)

ls()

load("my.file.with.m.R")

ls()


# Text files

write.table(m, file="my.text.file.txt")
write.csv(m, file="my.text.file.csv",row.names=F)

rm(m)

m <- read.table("my.text.file.txt")
m2 <- read.csv("my.text.file.csv")

str(m)
str(m2)
#m and m2 are data.frames! The old m was a matrix!