frankenstein_TSP.R

library(imager)
library(dplyr)
library(ggplot2)
library(scales)
library(TSP)

# Download the image
urlfile="http://ereaderbackgrounds.com/movies/bw/Frankenstein.jpg"

file="frankenstein.jpg"
if (!file.exists(file)) download.file(urlfile, destfile = file, mode = 'wb')

# Load, convert to grayscale, filter image (to convert it to bw) and sample
load.image(file) %>% 
  grayscale() %>%
  threshold("45%") %>% 
  as.cimg() %>% 
  as.data.frame()  %>% 
  sample_n(8000, weight=(1-value)) %>% 
  select(x,y) -> data

# Compute distances and solve TSP (it may take a minute)
as.TSP(dist(data)) %>% 
  solve_TSP(method = "arbitrary_insertion") %>% 
  as.integer() -> solution

# Rearrange the original points according the TSP output
data_to_plot <- data[solution,]

# A little bit of ggplot to plot results
ggplot(data_to_plot, aes(x,y)) +
    geom_path() +
    scale_y_continuous(trans=reverse_trans())+
    coord_fixed()+
    theme_void()

# Do you like the result? Save it! (Change the filename if you want)
ggsave("frankyTSP.png", dpi=600, width = 4, height = 5)