R4DS-2e Ch. 17

count()

{dplyr}

count unique values of variables

days()

{lubridate}

specify the number of days to be used in dates

library()

{base}

load R packages

is.na()

{base}

determine whether elements of vector are missing

mean()

{base}

calculate mean of elements of vector

mdy_hm()

{lubridate}

parse month, day, year and hour, minute

group_by()

{dplyr}

group data by levels of column

geom_point()

{ggplot2}

add layer of points to plot

dmy()

{lubridate}

parse dates as day, month, year

length()

{base}

return number of elements in a vector

today()

{lubridate}

return the current date

Sys.timezone()

{base}

return name of current time zone

summarize()

{dplyr}

summarize data usually by grouping variable

yday()

{lubridate}

extract day number of year

ggplot()

{ggplot2}

create a plotting area

wday()

{lubridate}

extract day number of week

months()

{lubridate}

specify the number of months to be used in dates

floor_date()

{lubridate}

round date-time down to floor

with_tz()

{lubridate}

return date-time in a different time zone

as_datetime()

{lubridate}

convert object to date-time

geom_bar()

{ggplot2}

create bar chart based on counts in data

now()

{lubridate}

return current date and time

ymd()

{lubridate}

parse dates with year, month, and day components

hour()

{lubridate}

return or set hour component of a date-time

filter()

{dplyr}

keep rows based on values of columns

month()

{lubridate}

return or set month component of a date-time

year()

{lubridate}

return or set year component of a date-time

head()

{utils}

return first rows of matrix, data frame, etc.

select()

{dplyr}

keep specified columns

n()

{dplyr}

return current group size

aes()

{ggplot2}

create aesthetic mappings between data and plot

mday()

{lubridate}

extract day number of month

update()

{stats}

update and refit a model

minute()

{lubridate}

return or set minute component of a date-time

OlsonNames()

{base}

return vector of all time zone names

read_csv()

{readr}

read comma delimited files

ends_with()

{tidyselect}

match column names that end with string

c()

{base}

create vector of numbers, characters, etc.

as_date()

{lubridate}

convert object to date

make_datetime()

{lubridate}

create date-times from numeric representations

mutate()

{dplyr}

create or modify data columns

mdy()

{lubridate}

parse dates as month, day, year

geom_line()

{ggplot2}

add layer of data lines to plot

day()

{lubridate}

get days component of date-time

force_tz()

{lubridate}

replace time zone to create new date-time

geom_freqpoly()

{ggplot2}

create frequency polygon

ymd_hms()

{lubridate}

parse dates and time

The end!