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