R basics

Question 1

How do you create a new working directory?

Answer 1

File -> New Project -> follow the instructions

Question 2

How do you create a new R script?

Answer 2

File -> New File -> R script

Question 3

Which tab do you use to use R as a calculator?

Answer 3

the console (bottom left)

Question 4

say you type in a letter (say “s”). How can you see a list of functions starting with s? How do you get the function without having to type in its whole name?

Answer 4

press tab. Scroll down to relevant function. Press tab again to complete.

Question 5

How can you round 1.44 to nearest whole number?

Answer 5

x

Question 6

How can you find the mean of the numbers 1 to 10?

Answer 6

x

Question 7

How can you add the numbers 1 to 10?

Answer 7

x

Question 8

What function can you use to see a codes datatype? (e.g. numeric, double, long etc.)

Answer 8

class(1.56)…..this will give you numeric

Question 9

I want to see if some code is an integer. How can I test this?

Answer 9

is.integer(10.2)….this will give false given the number is not an integer!

Question 10

What is a good package for working with strings (text?)

Answer 10

library(stringr)

Question 11

Using stringR - How does R tell you the output of something is a string?

Answer 11

It puts it in quotation marks -> e.g. would give output “foo”

Question 12

Using stringR - How to take a word in capitals to lower case?

Answer 12

str_to_lower(“FOO”)

Question 13

Using stringR - How to take a word in lower case to upper case?

Answer 13

str_to_upper(“foo”)

Question 14

Using stringR- How to make the first words of each letter a capital?

Answer 14

str_to_title(“foo bar”) = “Foo Bar”.

Question 15

Using stringR- How do you get the length of string?

Answer 15

str_length(“foo”)= “3”

Question 16

Using stringR- How do you get the two left characters in the word “foo”? i.e. how do you get “fo” as an output?

Answer 16

Use str_sub(“foo”,1,2) which gives “fo”. to get the right, you would use str_sub(“foo”, 2, 3).

Question 17

Using stringR- How can you concatenate in R?

Answer 17

use str_c(“foo”, “bar”, sep= “ “) to get “foo bar”.

Question 18

Using stringR- can you put one function inside another?

Answer 18

YES! str_to_upper(str_c(“foo”, “bar”)) gives “FOOBAR”!

Question 19

What characters show how to allocate a function?

Question 20

Functions- assign a and b 1 and 2 respectively then add them to make c.

Answer 20

a

Question 21

Functions- assign a and b “George” and “Pugh” respectively then concatante using stringr

Answer 21

a

Question 22

Whats the best function for working with dates?

Answer 22

lubridate

Question 23

Lubridate- how to convert excel date format (e.g. 17498) to a proper date?

Answer 23

as_date(17498) = “2017-11-28”)

Question 24

Lubridate - how to get current date and time

Answer 24

now() function

Question 25

Lubridate- how to get todays date?

Answer 25

today() function

Question 26

Lubridate- how can you get information on todays date (e.g. month, year, quarter etc).

Answer 26

1) date_today

Question 27

Lubridate- how to convert your dates to the most common format (i.e. 2018-01-01).

Answer 27

use dmy() function: e.g. dmy(“01 January 2018”) would convert to 2018-01-01 which is the universal function.

Question 28

Lubridate- I have a date but want to add one month- how do I do this?

Answer 28

jan01

Question 29

What are logical data types?

Answer 29

True, false and NA (NA not sure which one it is)

Question 30

Logical data- if 1 < 2, how do I print “1 is less than 2” in the console?

Answer 30

if(1<2) { print(“1 is less than 2”) }. This will print in bottom left hand corner.

Question 31

Logical data- if 2 words are the same, how do I print “Equality found”

Answer 31

word1

Question 32

Logical data - how to print FALSE FALSE TRUE to search for NA’s if you have a vector of (“a”, “b”, NA)

Answer 32

vector_NA

Question 33

Vectors- how to produce 5 a’s in a row?

Answer 33

rep(“a”,5)

Question 34

Vectors- how to get the sequence 1 3 5 7 9?

Answer 34

seq.int(1,10,2)

Question 35

Tables- how can you get the iris dataset in R?

Answer 35

Just code in “iris”

Question 36

Tables- How can you get a table to come up in R without it appearing in a horrible format in the console?

Answer 36

Type in….. View(iris)

Question 37

Tables -How can you see the top and bottom 5 entries in a table?

Answer 37

Use head() and tail()

Question 38

Tables- how can you see the column names in a table?

Answer 38

colnames(iris)

Question 39

Tables- what packages are good for getting excel/csv files into R?

Answer 39

readr and readxl (cheat sheets available on github).

Question 40

Table- How can you change the format of a date column in R?

Answer 40

Use drop down in table viewer to make sure column is highlighted as a date. Use lubirdate to change it!