Figures created for 656 class

polarization_656.R

library(dplyr)
library(ggplot2)
library(ggridges)
library(Kmisc)

# Brookings Party Unity Votes ==================================================
url <-
  "https://www.brookings.edu/wp-content/uploads/2017/01/vitalstats_ch8_tbl3.csv"
df <- read.csv(url)

p <- ggplot(
  df,
  aes(
    x = Year, y = PctPartyUnityVotes,
    group = Chamber, colour = Chamber, linetype = Chamber
  )
) +
  geom_line() +
  scale_x_continuous(breaks = seq(1950, 2021, by = 5)) +
  scale_color_viridis_d(end = 0.75, direction = -1) +
  theme_bw()

pdf("party_unity_votes_congress.pdf", width = 5, height = 4)
pdf_default(p) +
  theme(legend.position = "bottom")
dev.off()

# DW-NOMINATE Separation =======================================================
url <- "https://voteview.com/static/data/out/members/HSall_members.csv"
df <- read.csv(url)

congress <- df %>%
  filter(
    congress >= 87 & chamber != "President" &
      district_code != 0 & district_code != 98 & district_code != 99
  ) %>%
  filter(party_code == 100 | party_code == 200) %>%
  arrange(desc(congress)) %>%
  mutate(year1 = congress * 2 + 1787) %>%
  arrange(year1)

house <- congress %>% filter(chamber == "House")
senate <- congress %>% filter(chamber == "Senate")

p <- ggplot(
  house,
  aes(
    x = nominate_dim1, y = year1, group = interaction(year1, party_code),
    fill = factor(party_code)
  )
) +
  geom_density_ridges(
    scale = 7, size = 0.25, rel_min_height = 0.01, alpha = 0.5
  ) +
  theme_ridges(center = TRUE) +
  scale_x_continuous(
    limits = c(-1, 1.3), expand = c(0.01, 0),
    breaks = c(-1, -.75, -.5, -.25, 0, .25, .5, .75, 1)
  ) +
  scale_y_reverse(breaks = c(seq(2021, 1961, -10))) +
  scale_fill_manual(
    values = c("blue", "red"), breaks = c("100", "200"),
    labels = c("Democratic", "Republican"), name = "Party"
  ) +
  ggtitle("DW-NOMINATE by Party of U.S. House: 1961-2021") +
  ylab("First Year of Each Congress") +
  xlab("Distribution of 1st Dimension DW-NOMINATE by Party")

pdf("dwnom_house_1961_2021.pdf", width = 6, height = 4.5)
pdf_default(p) + 
  theme(legend.position = "bottom")
dev.off()