1.5

x <- 1.5

x

numeric(10)

c(1, 2, 3, 4, 5)

c(1, 2, c(3, 4, 5))

1:5

seq(1, 10, 2)

seq(3, length.out = 10)

1 + 1:5

TRUE

1 > 2

c(1, 2) > 2

c(1, 2) > c(2, 1)

c(2, 3) > c(1, 2, -1, 3)

1 %in% c(1, 2, 3)

c(1, 4) %in% c(1, 2, 3)

"hello, world!"

'hello, world!'

c("Hello", "World")

c("Hello", "World") == c('Hello', 'World')

c("Hello", "World") == "Hello, World"

cat("Is \"You\" a Chinese name?")

cat('Is "You" a Chinese name?')

v1 <- c(1, 2, 3, 4)

v1[2]

v1[2:4]

v1[-3]

a <- c(1, 3)

v1[a]

v1[c(1, 2, -3)]

v1[3:6]

v1[c(TRUE, FALSE, TRUE, FALSE)]

v1[2] <- 0

v1

v1[2:4] <- c(0, 1, 3)

v1

v1[c(TRUE, FALSE, TRUE, FALSE)] <- c(3, 2)

v1

v1[v1 <= 2]

v1[v1 ^ 2 - v1 + 1 >= 0]

v1[v1 <= 2] <- 0

v1

v1[10] <- 8

v1

x <- c(a = 1, b = 2, c = 3)

x

x["a"]

x[c("a", "c")]

x[c("a", "a", "c")]

names(x)

names(x) <- c("x", "y", "z")

x["z"]

names(x) <- NULL

x

x <- c(a = 1, b = 2, c = 3)

x["d"]

names(x["d"])

x[c("a", "d")]

x <- c(a = 1, b = 2, c = 3)

x["a"]

x[["a"]]

x[[c(1, 2)]]

x[[-1]]

x[["d"]]

class(c(1, 2, 3))

class(c(TRUE, TRUE, FALSE))

class(c("Hello", "World"))

is.numeric(c(1, 2, 3))

is.numeric(c(TRUE, TRUE, FALSE))

is.numeric(c("Hello", "World"))

strings <- c("1", "2", "3")

class(strings)

strings + 10

numbers <- as.numeric(strings)

numbers

class(numbers)

numbers + 10

as.numeric(c("1", "2", "3", "a"))

as.logical(c(-1, 0, 1, 2))

as.character(c(1, 2, 3))

as.character(c(TRUE, FALSE))

as.character(c(1, 2)) + c(2, 3)

c(1, 2, 3, 4) + 2

c(1, 2, 3) - c(2, 3, 4)

c(1, 2, 3) * c(2, 3, 4)

c(1, 2, 3) / c(2, 3, 4)

c(1, 2, 3) ^ 2

c(1, 2, 3) ^ c(2, 3, 4)

c(1, 2, 3, 14) %% 2

c(a = 1, b = 2, c = 3) + c(b = 2, c = 3, d = 4)

c(a = 1, b = 2, 3) + c(b = 2, c = 3, d = 4)

matrix(c(1, 2, 3, 2, 3, 4, 3, 4, 5), ncol = 3)

matrix(c(1, 2, 3,

4, 5, 6,

7, 8, 9), nrow = 3, byrow = FALSE)

matrix(c(1, 2, 3,

4, 5, 6,

7, 8, 9), nrow = 3, byrow = TRUE)

diag(1, nrow = 5)

matrix(c(1, 2, 3, 4, 5, 6, 7, 8, 9), nrow = 3, byrow = TRUE,

dimnames = list(c("r1", "r2", "r3"), c("c1", "c2", "c3")))

m1 <- matrix(c(1, 2, 3, 4, 5, 6, 7, 8, 9), ncol = 3)

rownames(m1) <- c("r1", "r2", "r3")

colnames(m1) <- c("c1", "c2", "c3")

m1

m1[1, 2]

m1[1:2, 2:3]

m1[1,]

m1[,2]

m1[1:2,]

m1[, 2:3]

m1[-1,]

m1[,-2]

m1[c("r1", "r3"), c("c1", "c3")]

m1[1]

m1[9]

m1[3:7]

m1 > 3

m1[m1 > 3]

m1 + m1

m1 - 2*m1

m1 * m1

m1 / m1

m1 ^ 2

m1 %*% m1

t(m1)

a1 <- array(c(0, 1, 2, 3, 4, 5, 6, 7, 8, 9), dim = c(1, 5, 2))

a1

a1 <- array(c(0, 1, 2, 3, 4, 5, 6, 7, 8, 9), dim = c(1, 5, 2),

dimnames = list(c("r1"), c("c1", "c2", "c3", "c4", "c5"), c("k1", "k2")))

a1

a0 <- array(c(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10), dim = c(1, 5, 2))

dimnames(a0) <- list(c("r1"), c("c1", "c2", "c3", "c4", "c5"), c("k1", "k2"))

a0

a1[1,,]

a1[, 2,]

a1[,,1]

a1[1, 1, 1]

a1[1, 2:4, 1:2]

a1[c("r1"), c("c1", "c3"), "k1"]

l0 <- list(1, c(TRUE, FALSE), c("a", "b", "c"))

l0

l1 <- list(x = 1, y = c(TRUE, FALSE), z = c("a", "b", "c"))

l1

l1$x

l1$y

l1$z

l1$m

l1[[2]]

l1[["y"]]

member <- "z" # you can dynamically determine which member to extract

l1[[member]]

l1["x"]

l1[c("x", "y")]

l1[1]

l1[c(1, 2)]

l1[c(TRUE, FALSE, TRUE)]

names(l1) <- c("A","B","C")

l1

names(l1) <- NULL

l1

l1 <- list(x = 1, y = c(TRUE, FALSE), z = c("a", "b", "c"))

l1$x <- 0

l1$m <- 4

l1

l1[c("y", "z")] <- list(y = "new value for y", z = c(1, 2))

l1

l1$x <- NULL

l1

l1[c("z", "m")] <- NULL

l1

l2 <- list(a = c(1, 2, 3), b = c("x", "y", "z", "w"))

is.list(l2)

is.list(l2$a)

l3 <- as.list(c(a = 1, b = 2, c = 3))

l3

l4 <- list(a = 1, b = 2, c = 3)

unlist(l4)

l4 <- list(a = 1, b = 2, c = "hello")

unlist(l4)

persons <- data.frame(Name = c("Ken", "Ashley", "Jennifer"),

Gender = c("Male", "Female", "Female"),

Age = c(24, 25, 23),

Major = c("Finance", "Statistics", "Computer Science"))

persons

l1 <- list(x = c(1, 2, 3), y = c("a", "b", "c"))

data.frame(l1)

as.data.frame(l1)

m1 <- matrix(c(1, 2, 3, 4, 5, 6, 7, 8, 9), nrow = 3, byrow = FALSE)

data.frame(m1)

as.data.frame(m1)

df1 <- data.frame(id = 1:5, x = c(0, 2, 1, -1, -3), y = c(0.5, 0.2, 0.1, 0.5, 0.9))

df1

colnames(df1) <- c("id", "level", "score")

rownames(df1) <- letters[1:5]

df1

df1$id

df1[[1]]

df1[1]

df1[1:2]

df1["level"]

df1[c("id", "score")]

df1[c(TRUE, FALSE, TRUE)]

df1[, "level"]

df1[, c("id", "level")]

df1[, 1:2]

df1[1:4,]

df1[c("c", "e"),]

df1[1:4, "id"]

df1[1:3, c("id", "score")]

df1[1:4,]["id"]

df1[1:4, "id", drop = FALSE]

df1$score >= 0.5

df1[df1$score >= 0.5, c("id", "level")]

rownames(df1) %in% c("a", "d", "e")

df1[rownames(df1) %in% c("a", "d", "e"), c("id", "score")]

df1$score <- c(0.6, 0.3, 0.2, 0.4, 0.8)

df1

df1["score"] <- c(0.8, 0.5, 0.2, 0.4, 0.8)

df1

df1[["score"]] <- c(0.4, 0.5, 0.2, 0.8, 0.4)

df1

df1[c("level", "score")] <- list(level = c(1, 2, 1, 0, 0), score = c(0.1, 0.2, 0.3, 0.4, 0.5))

df1

df1[1:3, "level"] <- c(-1, 0, 1)

df1

df1[1:2, c("level", "score")] <- list(level = c(0, 0), score = c(0.9, 1.0))

df1

str(persons)

persons[1, "Name"] <- "John"

persons

persons <- data.frame(Name = c("Ken", "Ashley", "Jennifer"),

Gender = factor(c("Male", "Female", "Female")),

Age = c(24, 25, 23),

Major = c("Finance", "Statistics", "Computer Science"),

stringsAsFactors = FALSE)

str(persons)

summary(persons)

rbind(persons, data.frame(Name = "John", Gender = "Male", Age = 25, Major = "Statistics"))

cbind(persons, Registered = c(TRUE, TRUE, FALSE), Projects = c(3, 2, 3))

expand.grid(type = c("A", "B"), class = c("M", "L", "XL"))

read.csv("data/persons.csv")

write.csv(persons, "data/persons.csv", row.names = FALSE, quote = FALSE)

add <- function(x, y) {

x + y

}

add(2, 3)

add(c(2, 3), 4)

add(as.Date("2014-06-01"), 1)

add(list(a = 1), list(a = 2))

calc <- function(x, y, type) {

if (type == "add") {

x + y

} else if (type == "minus") {

x - y

} else if (type == "multiply") {

x * y

} else if (type == "divide") {

x / y

} else {

stop("Unknown type of operation")

}

}

calc(2, 3, "minus")

calc(c(2, 5), c(3, 6), "divide")

calc(as.Date("2014-06-01"), 3, "add")

calc(1, 2, "what")

calc(1, 2, c("add", "minue"))

calc <- function(x, y, type) {

if (length(type) > 1L) stop("Only a single type is accepted")

if (type == "add") {

x + y

} else if (type == "minus") {

x - y

} else if (type == "multiply") {

x*y

} else if (type == "divide") {

x / y

} else {

stop("Unknown type of operation")

}

}

calc(1, 2, c("add", "minue"))

increase <- function(x, y = 1) {

x + y

}

increase(1)

increase(c(1, 2, 3))