simulate relationships from a logistic curve, about Dragons because why not

simulate_logistic.R

library(tidyverse)
set.seed(4812)
islands <- data_frame(area = 
                        # runif(35, min = 0, max = 29)
                        rlnorm(35, meanlog = log(5), sdlog = log(3))
                      )
                      
dragon_response <- function(b0, b1){
  force(b0)
  force(b1)
  function(v) {
    rethinking::logistic(b0 + b1 * v)
  }
}

library(gganimate)
purrr::rerun(20, 
             islands %>% 
               mutate(area_centered = log(area) - mean(log(area)),
                      p_dragon = map_dbl(area_centered, dragon_response(1.1, 0.5)),
                      is_dragon = rbinom(length(p_dragon), 1, p_dragon))) %>% 
  bind_rows(.id = "frame") %>% 
  ggplot(aes(x = log(area), y = is_dragon, frame = frame)) +
  geom_point() +
  stat_smooth(method = "glm", method.args = list(family = "binomial")) + 
  geom_line(aes(x = area_centered + mean(log(area)), y = p_dragon)) + 
  theme_minimal()+
  theme(text = element_text(size = 16)) + 
  NULL

gganimate(interval = .2, title_frame = FALSE)