R Objects:

R has five basic or “atomic” classes of objects:

• Numeric – Also known as Double. The default type when dealing with numbers. – Examples: 1, 1.0, 42.5
• Integer – Examples: 1L, 2L, 42L
• Complex – Example: 4 + 2i
• Logical – Two possible values: TRUE and FALSE – You can also use T and F, but this is not recommended. – NA is also considered logical.
• Character – Examples: “a”, “Statistics”, “1 plus 2.”

Other Objects:

Inf is infinity. You can have either positive or negative infinity.

1/0

Output:

[1] Inf

1/Inf

Output:

[1] 0

NaN means Not a number. It’s an undefined value.

0/0

Output:

[1] NaN

Attributes:

R objects can have attributes, which are like metadata for the object. These metadata can be very useful in that they help to describe the object.

• names, dimnames
• dimensions (e.g. matrices, arrays)
• class (e.g. integer, numeric)
• length
• other user-defined attributes/metadata

We will use each of these function later in this section wherever is required.

Attributes of an object (if any) can be accessed using the attributes() function. Not all R objects contain attributes, in which case the attributes() function returns NULL.

 attributes(iris)  #iris is a dataset

Output:

$names
[1] "Sepal.Length" "Sepal.Width" "Petal.Length" "Petal.Width" "Species"

$row.names
[1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
[19] 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
[37] 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54
[55] 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72
[73] 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90
[91] 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108
[109] 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126
[127] 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144
[145] 145 146 147 148 149 150

$class
[1] “data.frame”

 

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