Utility

Question 1

Which function calculates the absolute value of a vector of numerical values, element-wise?

Answer 1

abs()

Ex: abs(my_vector)

Question 2

Which function rounds each element of a vector to the nearest integer value?

Answer 2

round()

Ex: round(my_vector)

Question 3

Which function calculates the arithmetic mean of a vector of numeric values?

Answer 3

mean()

Ex: mean(my_vector)

Question 4

Which function creates a series of numbers, and what are the inputs to this function?

Answer 4

seq()

The seq function generates a sequence of numbers from x to y, incrementing or decrementing by z.

Ex: seq(x, y, by = z)

Question 5

Which function replicates its input, and what are its inputs?

Answer 5

rep()

The first input to rep is the vector or list to be replicated. The times input repeats the input vector a specified number of times. The each input repeats each element a specified number of times.

Ex: rep(my_vector, times = 10)

Question 6

How can you reverse the order of the sort() function?

Answer 6

By setting decreasing = TRUE

Question 7

What function can you use to check the type of your data structure?

Answer 7

is.___

Ex: is.list(my_object), is.vector(my_object), etc.

Question 8

What function can you use to attempt to transform one data type into another?

Answer 8

as.___

Ex: as.list(my_vector), etc.

Question 9

Which function attempts to convert a list to a vector?

Answer 9

unlist()

Ex: unlist(my_list)

Question 10

Which function reverses the order of the elements in a list?

Answer 10

rev()

Ex: rev(my_list)

Question 11

Which function adds the first inputted list to the end of the second inputted list?

Answer 11

append()

Ex: append(my_list1, my_list2)

Question 12

Which function checks if a given pattern exists in each string in a vector?

Answer 12

grepl()

Ex: grepl(pattern = “a”, x = my_vector)

Question 13

How can you use grepl to check if a pattern exists at the beginning or end of a string?

Answer 13

Include a ^ at the beginning of the pattern or a $ at the end.

Ex: grepl(pattern = “^a”, x = my_vector)

Ex: grepl(pattern = “a$”, x = my_vector)

Question 14

Which function returns a vector of indices whose elements contained the inputted pattern?

Answer 14

grep()

Ex: grep(pattern =”a”, x = my_vector)

Question 15

Which function finds and replaces every instance of a certain pattern in a vector of strings?

Answer 15

sub()

Ex: sub(pattern = “a”, replacement = “b”, x = my_vector)

Question 16

What is the difference between the sub and gsub functions?

Answer 16

While the sub function only replaces the first match in each string, gsub replaces every match.

Question 17

How can you give multiple options inside grep, grepl, sub, or gsub?

Answer 17

Using the | operator.

Ex: gsub(pattern = “a|i”, replacement = “b”, x = my_vector)