• We can put functions inside of functions
  • Math: \(f(g(x))\)
  • R: as.data.frame(read.csv("file.csv"))
• Or we can think of the output of one function as the input of another
  • Math: \(y = g(x)\) then \(f(y)\)
  • R: read.csv("file.csv") %>% as.data.frame()
• Using dplyr we can pipe the output of one function into another using %>%.

From Hadley Wickham:

x %>% f(y)
# is the same as:
f(x,y)

gapminder %>%
  group_by(continent, country) %>%
  nest()
# Same as:
nest(group_by(gapminder,continent,country))

Your code is how you communicate with others (especially your future self).

If it doesn't make any difference to the computer, you might as well write your code in a way that makes it easier for you to think about it and find errors.