Practice Questions
*(also see "More Practice Questions" below)*
46
44.
Practice Questions - TOPICS: Dataframes, & | !
r notes
About This Website
1
1.
Installing and using R
2
2.
variables, integer division and remainder operators
3
3.
Order of Operations in R
4
4.
Using some built-in functions
5
5.
User defined functions
6
6.
deubugger (also known as the "browser")
7
7.
modes of data: "numeric","logical","character",etc.
8
8.
NA is.na() na.rm argument
9
9.
Indexing with positive numbers
10
10.
Indexing with NEGATIVE numbers
11
11.
Logical vectors, relational (AKA logical) operators, ifelse
12
12a.
Indexing with logicals, e.g. someVector [ c(TRUE, FALSE, TRUE) ]
13
12b.
Automatic (or "implicit") conversions - numeric to logical - logical to numeric
14
12c.
(a) EXCLAMATION POINT (i.e the "not" operator) (b) is.na( LOGICAL_VECTOR )
15
13.
"character" values (also known as "strings"), cat(), nchar(), paste(), paste0()
16
14.
Using cat to help debug your code.
17
15.
Parallel vectors
18
16.
%in%
19
17.
"GLOBAL VARIABLES" vs "LOCAL VARIABLES"
20
18.
logical operators ! (not) & (and) | (or)
21
19.
scientific notation *~(longer version)~*
22
20.
scientific notation *~(abbridged version)~*
23
21.
implicit and explicit conversions
24
22.
intro to "lists" - i.e. collections of any R objects
25
23.
[[double-brackets]]
26
24.
Modifying Lists: (1) removing items (2) adding items (3) replacing items
27
25.
NAMED LISTS
28
26.
lapply ( SOME_LIST , SOME_FUNCTION )
29
27.
attributes
30
28.
matrices
31
29.
factors
32
30.
dataframes
33
31.
cbind and rbind (to combine dataframes)
34
32.
"if / else if / else" constructs
35
33.
while loops.
36
34.
for loops
Practice Questions
*(also see "More Practice Questions" below)*
37
35.
FINAL EXAM (2023) - Questions to study (ie. everything)
38
36.
Practice Questions - TOPIC: Vectors1
39
37.
Practice Questions - TOPIC: Vectors2
40
38.
Practice Questions - TOPIC: Assorted Topics
41
39.
Practice Questions - TOPIC: Dataframes
42
40.
Practice Questions - TOPIC: User Defined Functions
43
41.
Practice Questions - TOPICS: Parallel Vectors, &, |, scientific notation, etc.
44
42.
Practice Questions - TOPIC: Lists and Dataframes.
45
43.
Practice Questions - TOPIC: loops (writing code)
46
44.
Practice Questions - TOPICS: Dataframes, & | !
47
45.
Practice Questions - TOPICS: cat, loops (reading code)
Appendices
A
A.
R Studio Hotkeys
B
B.
DO NOT use parentheses when they are clearly not necessary.
C
C.
matching braces, indentation
D
D.
How to hide/show portions of code in RStudio ("code folding")
Practice Questions
*(also see "More Practice Questions" below)*
46
44.
Practice Questions - TOPICS: Dataframes, & | !
46
44.
Practice Questions - TOPICS: Dataframes, & | !
Click
here
for the questions.
Click
here
for the answers.
45
43.
Practice Questions - TOPIC: loops (writing code)
47
45.
Practice Questions - TOPICS: cat, loops (reading code)