R Programming

data_frames.R

x <- data.frame(x = 1:3, y = c(F, T, T))
#=> x     y
# 1 1 FALSE
# 2 2  TRUE
# 3 3  TRUE

nrow(x)
#=> [1] 3
ncol(x)
#=> [1] 2

factors_1.R

x <- factor(c("a", "b", "b", "a", "a", "b"))

#=> [1] a b b a a b
# Levels: a b

table(x)

#=> a b 
# 3 3 

unclass(x)
#=> [1] 1 2 2 1 1 2
# attr(,"levels")
# [1] "a" "b"

factors_2.R

x <- factor(c("hello", "bye", "bye", "hello", "bye"), levels = c("hello", "bye"))

#=> [1] hello bye   bye   hello bye  
# Levels: hello bye

factors_3.R

x <- factor(c("hello", "bye", "bye", "hello", "bye"))

#=> [1] hello bye   bye   hello bye  
# Levels: bye hello

lists.R

x <- list(FALSE, "a", 5.5, 1)
#=> [[1]]
#[1] FALSE

#[[2]]
#[1] "a"

#[[3]]
#[1] 5.5

#[[4]]
#[1] 1

matrices_1.R

m <- matrix(nrow = 5, ncol = 4)

#=>  [,1] [,2] [,3] [,4]
#[1,] NA   NA   NA   NA
#[2,] NA   NA   NA   NA
#[3,] NA   NA   NA   NA
#[4,] NA   NA   NA   NA
#[5,] NA   NA   NA   NA

dim(m)
#=> [1] 5 4

matrices_2.R

m <- matrix(1:15, nrow = 5, ncol = 2)
#=> [,1] [,2]
#[1,] 1    6
#[2,] 2    7
#[3,] 3    8
#[4,] 4    9
#[5,] 5   10

m <- matrix(1:10, nrow = 5, ncol = 5)

#=> [,1] [,2] [,3] [,4] [,5]
#[1,] 1    6    1    6    1
#[2,] 2    7    2    7    2
#[3,] 3    8    3    8    3
#[4,] 4    9    4    9    4
#[5,] 5   10    5   10    5

matrices_3.R

m <- 1:15
dim(m) <- c(3, 5)

#=> [,1] [,2] [,3] [,4] [,5]
#[1,] 1    4    7   10   13
#[2,] 2    5    8   11   14
#[3,] 3    6    9   12   15

matrices_4.R

x <- 1:4
y <- 10:13
cbind(x, y)

#=>   x  y
#[1,] 1 10
#[2,] 2 11
#[3,] 3 12
#[4,] 4 13

rbind(x, y)
#=> [,1] [,2] [,3] [,4]
#x   1    2    3    4
#y   10   11   12   13

missing_values.R

is.na(NA)
#=> [1] TRUE
is.nan(NA)
#=> [1] FALSE
is.nan(NaN)
#=> [1] TRUE
is.na(NaN)
#=> [1] TRUE

x <- c(1, NA, 10, 3)
is.na(x)
#=> [1] FALSE  TRUE FALSE FALSE
is.nan(x)
#=> [1] FALSE FALSE FALSE FALSE

y <- c(NaN, NA, 0, 10)
is.na(y)
#=>[1]  TRUE  TRUE FALSE FALSE
is.nan(y)
#=>[1]  TRUE FALSE FALSE FALSE

names_1.R

x <- 1:3
names(x)
#=> NULL
names(x) <- c("one", "two", "three")
#=> one   two three 
#    1     2     3 
names(x)
#=> [1] "one"   "two"   "three"

names_2.R

x <- list(one = 1, two = 2, three = 3)

#$one
#[1] 1

#$two
#[1] 2

#$three
#[1] 3

names_3.R

m <- matrix(1:4, nrow = 2, ncol = 2)
dimnames(m) <- list(c("a", "b"), c("c", "d"))

#=> c d
# a 1 3
# b 2 4

vectors_1.R

x <- c(1,2)
#=> [1] 1 2

x <- c(TRUE, FALSE)
#=> [1]  TRUE FALSE

x <- 1:10
#=> [1]  1  2  3  4  5  6  7  8  9 10

x <- c("hello", "world")
#=> [1] "hello" "world"

x <- vector("character", length = 5)
#=> [1] "" "" "" "" ""

vectors_2.R

x <- c(4, "a")
#=> [1] "4" "a"

x <- c(FALSE, 0)
#=> [1] 0 0

x <- c(TRUE, "t")
#=> [1] "TRUE" "t"   

vectors_3.R

x <- 1:2
class(x)
#=> [1] "integer"

as.numeric(x)
#=> [1] 1 2

as.logical(x)
#=> [1] TRUE TRUE

as.character(x)
#=> [1] "1" "2"

x <- c("m", "e", "g")
as.numeric(x)
#=> [1] NA NA NA
#Warning message:
#NAs introduced by coercion 

as.logical(x)
#=> [1] NA NA NA