Arguments

Question 1

How do you create a vector?

Answer 1

c (…)

Question 2

How do you calculate the sum of all elements in a vector?

Answer 2

Sum (any_vector)

Question 3

How do you create a matrix?

Answer 3

matrix(…)

Question 4

How do you fill in the data by row in a matrix?

Answer 4

byrow = TRUE

Question 5

How do you indicate the number of rows in a matrix?

Answer 5

nrow =

Question 6

How do you calculate the totals for each row of a matrix?

Answer 6

rowSums (any_matrix)

Question 7

How do you had a column or multiple columns to a matrix?

Answer 7

cbind( any matrix or vector)

Question 8

How do you check the contents of a workspace?

Answer 8

ls ( )

Question 9

How do you select all elements of a row or column?

Answer 9

any_matrix [1,] or any_matrix [,1]

Question 10

What is a factor?

Answer 10

A factor refers to a statistical data type used to store categorical variables.

Question 11

What is a categorical variable?

Answer 11

A variable that can belong to a limited number of categories.

Question 12

What is a continuous variable?

Answer 12

A variable that can belong to an infinite number of values.

Question 13

What is a nominal variable?

Answer 13

A variable without an implied order

Question 14

What is a nominal variable?

Answer 14

A variable with an implied order. (High, Medium, Low)

Question 15

How do you tell a vector that it is nominal or ordered?

Answer 15

factor( any_vector, order = TRUE, levels = c (“High”, “Medium”, “Low”)

Question 16

How do you specify the levels when creating a vector?

Answer 16

levels ( )

Question 17

How do you get the sum total of each factor in the data set?

Answer 17

summary(any vector or matrix)

Question 18

how do you show only the first observations in a data frame?

Answer 18

head ( any matrix or vector)

Question 19

how do you get the last observations in a data set?

Answer 19

tail (any vector or matrix)

Question 20

What does str( ) do?

Answer 20

Tells you: 
Total number of observations
Total number of variables
Full list of variable names
Data type of each variable
The first observations

Question 21

Vectors

Answer 21

(one dimensional array): can hold numeric, character or logical values. The elements in a vector all have the same data type

Question 22

Matrices

Answer 22

(two dimensional array): can hold numeric, character or logical values. The elements in a matrix all have the same data type.

Question 23

Data Frames

Answer 23

(two-dimensional objects): can hold numeric, character or logical values. Within a column all elements have the same data type, but different columns can be of different data type.

Question 24

A list in R

Answer 24

allows you to gather a variety of objects under one name (that is, the name of the list) in an ordered way. These objects can be matrices, vectors, data frames, even other lists, etc. It is not even required that these objects are related to each other in any way.

Question 25

what does == do?

Answer 25

checks the equality of two variables and outputs TRUE or FALSE

Question 26

trim = x/y

Answer 26

trim =, takes whatever fraction you input and applies it to the number of data inputs, and then removes that number from both the beginning and ending or highest and lowest points of the data inputs.