Lab2 - R Data Types and Data Structures

Question 1

What does dynamically typed mean in R?

Answer 1

Types inferred when values are created

Question 2

Which type represents strings?

Answer 2

Character

Question 3

Which type represents whole numbers?

Answer 3

Integer (L suffix)

Question 4

Which type represents decimal numbers?

Answer 4

Numeric

Question 5

Which type holds complex numbers?

Answer 5

Numeric with imaginary component

Question 6

Which type holds boolean values?

Answer 6

1. Logical (TRUE/FALSE)

Question 7

Which function checks numeric type?

Answer 7

is.numeric()

Question 8

Which function coerces to integer?

Answer 8

as.integer()

Question 9

Which functions round numbers? ( 3 )

Answer 9

round(), ceiling(), floor()

Question 10

Which functions compute basic statistics? ( 5 )

Answer 10

sum(), mean(), sd(), min(), max()

Question 11

Which function summarizes data frames?

Answer 11

summary()

Question 12

Which functions create sequences and repetitions?

Answer 12

seq(), rep()

Question 13

Which function checks character type?

Answer 13

is.character()

as.character()

Question 14

List out function for string concatenation

Answer 14

1. paste()
2. paste0()
3. sprintf()

Question 15

Which function counts characters?

Answer 15

1. nchar()

Question 16

Which functions extract substrings? ( 2 )

Answer 16

1. substr()
2. substring()

Question 17

Which functions change case?

Answer 17

1. tolower()
2. toupper()

Question 18

Which functions match patterns?

Answer 18

1. grep()
2. grepl()

Question 19

Which function splits strings?

Answer 19

1. strsplit()

Question 20

Which function checks logical type?

Answer 20

1. is.logical()

Question 21

Which function coerces to logical?

Answer 21

1. as.logical()

Question 22

Which functions test logic across vectors? ( 2 )

Answer 22

1. any()
2. all()

Question 23

Which function returns TRUE indices?

Returns the index of the first occurrence of TRUE or the maximum number if a numeric vector is provided

Answer 23

1. which()

Question 24

Which function returns index of first max?

Answer 24

1. which.max()

Question 25

Which function shows low-level type?

Answer 25

1. typeof()

Question 26

Which function shows high-level type?

Answer 26

1. class()

Question 27

What is an R vector?

Answer 27

One-dimensional, same-type elements

Question 28

How to create a vector?

Answer 28

Use c() annotation ``` c(TRUE, FALSE, T, F, F) ```

Question 29

How to subset a vector?

Answer 29

Use [ ] with 1-based indices

Question 30

What is an R list?

Answer 30

One-dimensional, mixed-type elements ``` list(c("Male", "Female", "Female", "Male", "Female")) ```

Question 31

What is the starting index in R?

Answer 31

1. 1 ## Footnote Not 0

Question 32

How to subset list elements?

Answer 32

Use [ ], [[ ]], or $

Question 33

What is an R matrix?

Answer 33

Two-dimensional, single-type elements ``` matrix(1:6, nrow=2, ncol=3) ```

Question 34

How to create a matrix?

Answer 34

1. Use matrix()

Question 35

How to subset a matrix?

Answer 35

Use [row, col]

Question 36

What is an R array?

Answer 36

Multi-dimensional, single-type elements"

Question 37

How to create an array?

Answer 37

Use array()

Question 38

How to subset an array?

Answer 38

Use [i, j, k] with indices i = row j = col z = matrix layer

Question 39

Which function gets object names?

Answer 39

1. names()

Question 40

Which function returns object length?

Answer 40

1. length()

Question 41

Which functions get dimensions? ( 3 )

Answer 41

1. dim() 2. nrow() 3. ncol()

Question 42

Which function flattens a list?

Answer 42

unlist()

Question 43

Which functions combine by rows/columns?

Answer 43

1. rbind() 2. cbind()

Question 44

Which operator checks membership?

Answer 44

"%in%

Question 45

Which function samples values?

Answer 45

1. sample()

Question 46

What is a factor?

Answer 46

Efficient representation of categorical data

Question 47

What are factor levels?

Answer 47

Unique categories stored as labels

Question 48

What are integer codes in factors?

Answer 48

Numeric mapping to levels

Question 49

How to access factor levels?

Answer 49

1. Use levels()

Question 50

How to access factor labels?

Answer 50

Use labels()

Question 51

What is the default structure for tabular data in R?

Answer 51

1. Data Frame ( data.frame )

Question 52

Why use data.table?

Answer 52

1. Higher Performance, Optimised for speed and memory efficiency 2. Supports in-place modification 3. Used where high-speed processing is required

Question 53

Why use Tibbles rather than data frame?

Answer 53

1. Modern and more user friendly alternative to data.frame 2. Displays tidier and cleaner data previews 3. Used in Tidyverse workflows

Question 54

Name key R structures for analysis.

Answer 54

1. Vectors 2. Factors 3. Data frames 4. Tibbles 5. Lists 6. Matrices