Vision Zero Visualization Blog Post Gist

Vision Zero - Accident Change

# Accident count percentage change
accident_p_vec <- c(0, tail(accident_n_dt$N, nrow(accident_n_dt) - 1) / 
                head(accident_n_dt$N, nrow(accident_n_dt) - 1) - 1)

# Number of registered vehicles in NYC
# https://dmv.ny.gov/about-dmv/statistical-summaries
reg_nyc <- data.table(Year = seq(2012, 2015),
                      Reg_num = c(1978392,
                                  2016158,
                                  2057433,
                                  2107321))

# Registration percentage change
reg_p_vec <- c(0, tail(reg_nyc$Reg_num, nrow(reg_nyc)-1) /
                 head(reg_nyc$Reg_num, nrow(reg_nyc)-1) - 1)

temp <- data.frame(PERIOD = rep(sort(unique(work_dt$PERIOD)), 2),
                   TYPE   = rep(c('Motor Vehicle Collision',
                                  'Vehicle Registration in NYC'), each = 4),
                   VALUE  = c(accident_p_vec, reg_p_vec))

# Visualize changes
ggplot(data = temp,
       aes(x = PERIOD, y = VALUE, color = TYPE, group = TYPE)) + 
  geom_point(size = 3) +
  geom_line(size = 2, alpha = .8) +
  scale_y_continuous(labels = scales::percent) +
  theme(legend.position = 'none') +
  labs(title = 'Yearly Growth Rate', y = '% Growth Since Last Year') +
  facet_wrap( ~ TYPE, nrow = 2)