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