Module 3.2 Objects, Numbers and Attributes

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R Programming for Data Science, by Roger D. Peng

1 Objects

x <- c(1, 2, 3.4)
x

[1] 1.0 2.0 3.4

y <- c (1,2, 3.4567)
y

[1] 1.0000 2.0000 3.4567

z <- c (TRUE, T, F)
z

[1]  TRUE  TRUE FALSE

class(z)

[1] "logical"

class (x)

[1] "numeric"

r <- c(1+0i,2+3i, 4)
r

[1] 1+0i 2+3i 4+0i

-21/0

[1] -Inf

0/0

[1] NaN

class(NaN)

[1] "numeric"

1+Inf

[1] Inf

Inf-Inf

[1] NaN

0^0

[1] 1

Inf * -Inf

[1] -Inf

2 Numbers

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

[1] "1" "2" "3" "4" "5" "a"

c(TRUE, 0, 1, 0, -1)

[1]  1  0  1  0 -1

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

[1] 1+0i 2+0i 3+0i 1+2i

as.character(x)

[1] "1"   "2"   "3.4"

-1:5

[1] -1  0  1  2  3  4  5

as.logical(-1:5)

[1]  TRUE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE

as.logical(1.2)

[1] TRUE

as.logical("TRUE")

[1] TRUE

as.logical ("acb")

[1] NA

x

[1] 1.0 2.0 3.4

as.complex(x)

[1] 1.0+0i 2.0+0i 3.4+0i

3 Attributes

x <- 1:5
y <- 6:10
z <- c (-4,0,3,12,5)

M <- rbind (x,y,z)
M

  [,1] [,2] [,3] [,4] [,5]
x    1    2    3    4    5
y    6    7    8    9   10
z   -4    0    3   12    5

dimnames (M) [[2]] <- c("col1", "col2", "col3", "col4", "col5")
dimnames (M) [[1]] <- c("row1", "row2", "row3")
attributes(M)

$dim
[1] 3 5

$dimnames
$dimnames[[1]]
[1] "row1" "row2" "row3"

$dimnames[[2]]
[1] "col1" "col2" "col3" "col4" "col5"

M

     col1 col2 col3 col4 col5
row1    1    2    3    4    5
row2    6    7    8    9   10
row3   -4    0    3   12    5

class(M)

[1] "matrix" "array" 

typeof(M)

[1] "double"

dimnames(M)

[[1]]
[1] "row1" "row2" "row3"

[[2]]
[1] "col1" "col2" "col3" "col4" "col5"

#Lists

x1 <- 1:3                   #vector of integers
x2 <- list (1L, 3.4, TRUE)  #list
x3 <- 1+3i                  #vector of complex of length 1

length(x1)

[1] 3

length(x2)

[1] 3

length(x3)

[1] 1

list (x1,x2,x3)

[[1]]
[1] 1 2 3

[[2]]
[[2]][[1]]
[1] 1

[[2]][[2]]
[1] 3.4

[[2]][[3]]
[1] TRUE


[[3]]
[1] 1+3i

list(x1,x2,M)

[[1]]
[1] 1 2 3

[[2]]
[[2]][[1]]
[1] 1

[[2]][[2]]
[1] 3.4

[[2]][[3]]
[1] TRUE


[[3]]
     col1 col2 col3 col4 col5
row1    1    2    3    4    5
row2    6    7    8    9   10
row3   -4    0    3   12    5

A <- array(1:24, dim= c(2,3,4))

dim(A)

[1] 2 3 4

attributes(A)

$dim
[1] 2 3 4

class(NaN)

[1] "numeric"

1+NaN

[1] NaN

Inf-Inf

[1] NaN

-3 * Inf

[1] -Inf

Inf+NaN

[1] NaN

0*NaN

[1] NaN

NaN/NaN

[1] NaN