2. Working with Vectors

Question 1

Indexing vectors by position

Answer 1

Extract a single element:

vector[1]

Extract a range of elements:

vector[3:7]

Extract multiple elements:

vector[c(2,5,7)]

Question 2

Displaying data types

Answer 2

Display the data type of a vector:

typeof(vector)

Question 3

Naming vector elements

Answer 3

Assign name attributes to a vector:

names(vector) <- name_vector

Question 4

Indexing vectors by name

Answer 4

Extract a single element:

vector[“name_2”]

Extract multiple elements:

vector[c(“name_1”, “name_2)]

Question 5

Logical operators

Answer 5

Less than: vector_1 < vector_2

Greater than: vector_1 > vector_2

Less than or equal to: vector_1 <= vector_2

Greater than or equal to: vector_1 >= vector_2

Equal to: vector_1 == vector_2

Not equal to: vector_1 != vector_2

Question 6

Logical indexing

Answer 6

Indexing into a numeric vector using a logical vector: numeric_vector[logical_vector]

Question 7

Performing arithmetic on vectors

Answer 7

Add, divide, or multiply vectors:

vector_1 + vector_2

vector_1 / vector_2

vector_1 * vector_2

Question 8

Concepts

Answer 8

R recognizes different data types:

• Numeric (3, 5.66, 199, 6)
• Character (“math”, “%”, “&”, “chem+math”)
• Logical (TRUE, FALSE)

R is a 1-indexed programming language, which means that the first element in a vector is assigned a position of one.

When performing operations on vectors of unequal length, R “recycles” values of the shorter vector until the two vectors are the same length.