quiz 2 functions

Question 1

str_length

Answer 1

returns number of the string (size?)

Question 2

str()

Answer 2

dataset structure (x)

Question 3

mutate()

Answer 3

add/change columns

Question 4

facet_wrap()

Answer 4

different graphs based on (~x) variable

Question 5

color =

Answer 5

color outside of (for points)

Question 6

dim()

Answer 6

dimentions

Question 7

fig.cap = “ “

Answer 7

caption (also can go in labs())

Question 8

summarize()

Answer 8

collapse data into one row /one value

Question 9

fig.alt = “ “

Answer 9

alternative text (also can go in labs())

Question 10

pivot_wider()

Answer 10

“widens” data, increasing the number of columns and decreasing the number of rows (data, names_from = name, values_from = values)

Question 11

geom_histogram()

Answer 11

histogram

Question 12

class()

Answer 12

return the values of the class attribute of an R object

Question 13

str_sub()

Answer 13

keeps a subset of characters in x, from start (a number indexing first letter to keep) to end (a number indexing last letter to keep) (x, start, end)

Question 14

fct_reorder()

Answer 14

reorder levels according to values of another variable

Question 15

group_by()

Answer 15

create groups

Question 16

filter()

Answer 16

select certain rows

Question 17

geom_point()

Answer 17

scatterplot

Question 18

select()

Answer 18

select certain columns

Question 19

semi_join()

Answer 19

return all rows from x with a match in y (x, y)

Question 20

str_replace()

Answer 20

finds the first part of x that matches the pattern and replaces it with replacement (x, pattern, replacement)

Question 21

nrow()

Answer 21

number of rows

Question 22

count()

Answer 22

count all rows in (x)

Question 23

anti_join()

Answer 23

return all rows from x without a match in y (x, y)

Question 24

geom_density()

Answer 24

density graph

Question 25

str_detect()

Answer 25

finds pattern in column x (x, pattern), returns true/false

Question 26

geom_bar()

Answer 26

bar graph

Question 27

pivot_longer()

Answer 27

"lengthens" data, increasing the number of rows and decreasing the number of columns (data, cols, names_to = "name", values_to = "values", values_drop_na = FALSE)

Question 28

fill =

Answer 28

fill inside of (for bars)

Question 29

inner_join()

Answer 29

only keeps observations from x that have a matching key in y (x, y)

Question 30

head()

Answer 30

first 6

Question 31

geom_smooth()

Answer 31

line based on least squares, but trend lines by default

Question 32

str_extract()

Answer 32

finds the *first* part of `x` that matches the `pattern` and takes it (x, pattern)

Question 33

fct_recode()

Answer 33

manually change levels (x, "new" = "old")

Question 34

geom_boxplot()

Answer 34

box plot

Question 35

str_replace_all()

Answer 35

finds *all* instances in `x` that matches the `pattern` and replaces it with `replacement` (x, pattern, replacement)

Question 36

arrange()

Answer 36

reorder data

Question 37

full_join()

Answer 37

keeps all observations in x and y (adds NA's)

Question 38

left_join()

Answer 38

keeps all observations in x (x, y)

Question 39

geom_line()

Answer 39

line graph

Question 40

str_to_lower()

Answer 40

all upper case letters in `x` to lower case (x)

Question 41

fct_relevel()

Answer 41

manually reorders levels (x, c("", "",""))