Lecture 1

Question 1

what’s on the RHS of RStudio (working environment)

Answer 1

output, variables

Question 2

what’s on the LHS of RStudio

Answer 2

top = instructions to R
bottom = console, type commands into R, get output back immediately

Question 3

does it matter to have space or no space in basic arithmetic in R console? (eg: 10*3 vs 10 * 3)

Answer 3

no

Question 4

what is the numerical operator commanding ‘power’? (eg: 2 to the power of 3)

Answer 4

numerical operator: ^

eg: 2^3

Question 5

what is the numerical operator commanding ‘multiplication’? (eg: 2 multiplied by 3)

Answer 5

numerical operator: *

eg: 2*3

Question 6

what is the numerical operator commanding ‘division’? (eg: 2 divided by 3)

Answer 6

numerical operator: /

eg: 2/3

Question 7

what is the numerical operator commanding ‘summation’? (eg: 2 summed by 3)

Answer 7

numerical operator: +

eg: 2+3

Question 8

what is the numerical operator commanding ‘subtraction’? (eg: 2 subtracted by 3)

Answer 8

numerical operator: +

eg: 2+3

Question 9

what is the logical operator commanding ‘equality’? (eg: 2 + 2 is equal to 4)

Answer 9

logical operator: ==

eg: 2+2 == 4

Question 10

what is the logical operator commanding ‘inequality’? (eg: 2 + 2 is NOT equal to 5)

Answer 10

logical operator: !=

eg: 2+2 != 5

Question 11

what is the R’s response to logical operators?

Answer 11

[1] TRUE
or
[1] FALSE

Question 12

what is the logical operator commanding ‘greater than’? (eg: 4 is greater than 2)

Answer 12

logical operator: >

eg: 4 > 2

Question 13

what is the logical operator commanding ‘greater than equal to’? (eg: 2 is greater than equal to 2)

Answer 13

logical operator: >=

eg: 2 >= 2

Question 14

what is the logical operator commanding ‘less than’? (eg: 2 is less than 4)

Answer 14

logical operator: <

eg: 2 < 4

Question 15

what is the logical operator commanding ‘less than equal to’? (eg: 2 less than equal to 5)

Answer 15

logical operator: <=

eg: 2 <= 5

Question 16

if T is TRUE, what would R response be when you input ‘T & T’

Answer 16

T & T = if T is TRUE AND T is TRUE, then output would be TRUE

Question 17

if T is TRUE, what would R response be when you input ‘T | T’

Answer 17

the logical operator ‘|’ means OR

hence T is TRUE OR T is TRUE, then output is TRUE

Question 18

if T is TRUE, what would R response be when you input ‘T | !T’

Answer 18

the logical operator ‘|’ means OR and the logical operator ! means NOT (!T = False)
hence T is TRUE OR NOT T is TRUE, then output is TRUE

Question 19

if T is TRUE, what would R response be when you input ‘T & !T’

Answer 19

the logical operator ‘&’ means AND and the logical operator ! means NOT
hence it reads: T is TRUE AND NOT T is TRUE, then output is FALSE

Question 20

what is T & F, T | F, T & !F, T | !F ???

Answer 20

FALSE, TRUE, TRUE, TRUE

Question 21

what is F & T, F | T, F & !T, F | !T

Answer 21

FALSE, TRUE, FALSE, FALSE

Question 22

what is the function sqrt() for

Answer 22

square root

Question 23

what would Sqrt() show

Answer 23

ERROR because functions in R are case-sensitive. square root function is sqrt() and not Sqrt()

Question 24

what is the function round()

Answer 24

round up or round down

Question 25

> round(3.24) ????

Answer 25

[1] 3

Question 26

what is an argument in function?

Answer 26

function is like a machine, it needs an argument for the machine to operate. eg: to make orange juice (output) you need juice maker machine (function) and inside the maker u need orange fruits (argument) a function would always expect one or more argument (eg: pancakes is made of milk, butter, eggs)

Question 27

> round(3.14159, 4) ???

Answer 27

in this case function round () has more than 1 argument. the argument means that you wanna round 3.14159 to 4 decimal places hence, [1] 3.1416

Question 28

> round(2, 3.14159) ?????

Answer 28

means that you wanna round 2 to 3.1415 significant figures --> order matters in functions! hence, [1] 2

Question 29

nesting function properties?

Answer 29

it works inside out. hence, the functions inside is worked out first, then after that outside

Question 30

types of variables?

Answer 30

- numerical: blackbox

Question 31

what kind of variable is age

Answer 31

numerical variable

Question 32

if age

Answer 32

1. 44 2. 64 adding a number to a variable does not change the content of that variable. age is still 34 even thought we added it by 10 in 1

Question 33

if q

Answer 33

ERROR

Question 34

requirement for variable names?

Answer 34

1. must start with a letter or a period 2. letters, numbers, periods c ("0" to "9") can be used 3. underscore (_) can be used, but is best avoided 4. name CANNOT contain space or characters like ?,+,!, #, %, (, ), etc 5. cannot contain reserved word like TRUE or functions used in R

Question 35

can you have underscore (_) in your variable name?

Answer 35

yes. underscore can be used, but is best avoided

Question 36

can variable name contain space?

Answer 36

no. CANNOT contain space

Question 37

can you put characters like ? in your variable name?

Answer 37

no, name CANNOT contain space or characters like ?,+,!, #, %, (, ), etc

Question 38

can you put a function name in your variable name?

Answer 38

no. cannot contain reserved word like TRUE or functions used in R

Question 39

advantages of creating vectors

Answer 39

they can store multiple values | they can be combined into data frames

Question 40

types of vectors

Answer 40

- numeric (atomic) vector --> number - character (atomic) vector --> name - logical (atomic) vector --> TRUE or FALSE

Question 41

what does "c()" function mean

Answer 41

it is basically saying to put all these values into this particular variable eg: > age age [1] 34 2 age contains the values 34 and 2. 1st element is 34 and 2nd element is 2

Question 42

what type of vector is involved in this console: > nerd nerd [1] TRUE FALSE

Answer 42

logical (atomic) vector.

Question 43

vector must:

Answer 43

contain the same time to be understandable. eg: you can't have numeric and character elements under the same vector at the same time

Question 44

if: | > person subject mark mark [subject == "RMHI"] ?????

Answer 44

what it means: marks for people in RMHI [1] 82 71

Question 45

if: | > person subject mark subject [mark >= 65 ]

Answer 45

what it means: subject where people get greater or equal to 65 [1] "RMHI", "RMHI", "ARMP"

Question 46

if: | > person subject mark mark [person == "ann" &+ subject == "RMHI" &+ mark < 50]

Answer 46

what it means: mark of people who's name is ANN, takes RMHI, and has mark above 50 response: numeric (0) since mark is numeric and there is no element that satisfy those criteria, then numeric (0) is just a vector that contains no elements

Question 47

what is a package in R?

Answer 47

- collection of user-written collections of functions, data. - 12000 packages in R - installed (in your computer) - loaded (made available for use in R session)