diversity-lines.R

gen_plot <- function(xvals = c(1,12), yvals = c(1,10), n = 10, 
                   distance = seq(-3,3,length.out =n),
                   seed = NULL, palette = c("red", "blue")){
  
  # adapted from: https://stackoverflow.com/questions/50275195/
  segment.shift <- function(x1,x2,y1,y2, d){
    
    # calculate vector
    v <- c(x2 - x1,y2 - y1)
    
    # normalize vector
    v <- v/sqrt((v[1]**2 + v[2]**2))
    
    # perpendicular unit vector
    vnp <- c( -v[2], v[1] )
    
    list(
      x1 = x1 + d*vnp[1], 
      x2 = x2 + d*vnp[1], 
      y1 = y1 + d*vnp[2], 
      y2 = y2 + d*vnp[2]
    )
    
  }
  
  set.seed(seed)
  my_df <- tibble(
    x1 = rep(xvals[1],n),
    x2 = rep(xvals[2],n),
    y1 = rep(yvals[1],n),
    y2 = rep(yvals[2],n),
    d = distance
  ) %>% 
    pmap_dfr(segment.shift) %>% 
    mutate(color = scales::col_numeric(palette = palette, domain = NULL)(x1)) 
  
  rand_vals <- my_df %>% 
    select(x1:y2) %>% 
    pmap_dfr(function(x1,x2,y1,y2){
      # find points on the line
      approx_vals <- approx(x=c(x1,x2), y =c(y1,y2), n = 50)
      
      # randomly shorten the line
      sub_vec <- sample(8:35, size = 1)
      # randomly select a "point" ahead of the shortened portion
      point_vec <- sub_vec - sample(3:8, size = 1, prob = seq(0.5, 0.1,length.out = 6))
      
      # grab the x/ycoords for the lines
      xval <- approx_vals$x[sub_vec]
      yval <- approx_vals$y[sub_vec]
      # grab the x/ycoords for the points
      xpt <- approx_vals$x[point_vec]
      ypt <- approx_vals$y[point_vec]
      # throw it in a list
      list(xstart = xval, ystart = yval, xpt =xpt, ypt = ypt)
    })
    
  
  my_df %>% 
    # extract the line/points coords
    mutate(x1 = rand_vals$xstart, y1 = rand_vals$ystart,
           xpt = rand_vals$xpt, ypt = rand_vals$ypt) %>% 
    ggplot() +
    geom_segment(aes(x = x1, y = y1, xend = x2, yend = y2, color = I(color)),
                 size = 8, lineend = "round") +
    geom_point(aes(x = xpt, y = ypt, color = I(color)), size = 8) +
    theme_void() +
    theme(plot.background = element_rect(fill = "white",color="white"),
          panel.background = element_rect(fill = "white",color="white"))
}


my_pal <- c("#f55a07", "#fa1500", "#942b2d", "#ee5299", "#c41a6c", "#742684", 
            "#00437c", "#0179e3", "#005f2e", "#809d29", "#3f8292", "#565656",
            "#f9de24", "#d08b3e", "#f95a00")


my_plot <- gen_plot(n = 15, palette = my_pal, distance = seq(-4,4.5, length.out =15), 
         seed = 1234) +
  coord_cartesian(xlim = c(-2,11), ylim = c(-2,8))

ggsave("myplot.png", my_plot, dpi = "retina", height = 6, width = 6)