Data 110 HW5

library(tidyverse)

── Attaching core tidyverse packages ──────────────────────── tidyverse 2.0.0 ──
✔ dplyr     1.1.4     ✔ readr     2.1.5
✔ forcats   1.0.0     ✔ stringr   1.5.1
✔ ggplot2   3.5.1     ✔ tibble    3.2.1
✔ lubridate 1.9.3     ✔ tidyr     1.3.1
✔ purrr     1.0.2     
── Conflicts ────────────────────────────────────────── tidyverse_conflicts() ──
✖ dplyr::filter() masks stats::filter()
✖ dplyr::lag()    masks stats::lag()
ℹ Use the conflicted package (<http://conflicted.r-lib.org/>) to force all conflicts to become errors

library(ggplot2)
library(dplyr)
nations <- read.csv("nations.csv")  

nations <- nations |>
  mutate(gdp_trillions = (gdp_percap * population) / 1000000000000)


selected_countries <- c("United States", "China", "Japan", "Germany")  

nations_filtered <- nations |>
  filter(country %in% selected_countries)

ggplot(nations_filtered, aes(x = year, y = gdp_trillions, color = country)) +
  geom_line(size = 1) +
  geom_point(size = 2) +
  scale_color_brewer(palette = "Set1") +
  labs(
    title = "GDP Trends of Selected Countries (Trillions USD)",
    x = "Year",
    y = "GDP (Trillions)",
    color = "Country"
  ) 

Warning: Using `size` aesthetic for lines was deprecated in ggplot2 3.4.0.
ℹ Please use `linewidth` instead.

regional_gdp <- nations |>
  group_by(region, year) |>
  summarise(GDP = sum(gdp_trillions, na.rm = TRUE))

`summarise()` has grouped output by 'region'. You can override using the
`.groups` argument.

ggplot(regional_gdp, aes(x = year, y = GDP, fill = region)) +
  geom_area(color = "white", size = 0.2) +
  scale_fill_brewer(palette = "Set2") +
  labs(
    title = "Regional GDP Over Time (Trillions USD)",
    x = "Year",
    y = "GDP (Trillions)",
    fill = "Region"
  )