Exercises: Simple Functions in R

1 Simple Functions in R

1.1 Instructions and Setup

library(gapminder)
data(gapminder)

Write these functions. Run the tests.

1.1.1 Life expectancy change

Write life_change() to return life expectancy in year2 minus year1 for a country. Return NA if either year is missing.

life_change <- function(country_name, year1, year2) {
  # Write code here
}

life_change("China", 1982, 2007)

NULL

life_change("India", 1952, 2007)

NULL

1.1.2 Compare countries

Write compare_yr() that accepts any number of country names and prints:

Country: YYYY lifeExp = __, gdpPercap = __

Each country gets its own line. Skip any countries not found.

Must specify year as an argument. Set year to 2007 by default.

Multiple countries can be passed via ....

# Note there are only a few unique years in the dataset, so we can check for valid years with unique()
unique(gapminder$year)

 [1] 1952 1957 1962 1967 1972 1977 1982 1987 1992 1997 2002 2007

compare_yr <- function(yr = 2007, ...) {
  # Write code here
}

compare_yr(2002, "Norway", "Italy", "India", "Brazil")

NULL