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Commit c923fb18 authored by Angie Liu's avatar Angie Liu
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Delete lab_2.R

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# Lab 2
# tidyverse
# install packages
install.packages("tidyverse")
# load packages
library(tidyverse)
require(tidyverse)
# the pipe operator -- %>%
?mtcars
mtcars
sqrt(mean(colSums(mtcars)))
mtcars %>% colSums %>% mean %>% sqrt
# x %>% f() f(x)
# x %>% f %>% g g(f(x))
# select columns -- select()
mtcars %>% select(mpg, cyl, hp)
mtcars %>% select(-am, -vs)
# select rows -- filter()
mtcars %>% filter(cyl == 8)
mtcars %>% filter(cyl == 8 & gear >= 5)
# create columns -- mutate()
mtcars %>% mutate(four_cyl = (cyl == 4), twice_hp = 2 * hp)
# sort -- arrange()
mtcars %>% arrange(vs)
mtcars %>% arrange(vs, desc(gear))
# exercise
mtcars %>%
select(-qsec) %>%
filter(carb > 2) %>%
mutate(twice_mpg = 2 * mpg) %>%
arrange(hp, disp, desc(vs))
# present basic statistics -- summarize()
# by group -- group_by()
mtcars %>% summarise(mean(hp), sum(mpg), min(gear), median(carb), count=n())
mtcars %>% group_by(vs) %>% summarise(mean(hp), n())
?group_by
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