text: #!/usr/bin/env python3
  
  import matplotlib.pyplot as plt
  import numpy as np
  import sys
  
  if __name__ == "__main__":
      filename = sys.argv[1]
      data = np.genfromtxt(filename, delimiter=",", names=True)
      a = data[data.dtype.names[0]]
      b = data[data.dtype.names[1]]
      max_a = int(max(a))
      max_b = int(max(b))
      min_a = int(min(a))
      min_b = int(min(b))
      d = np.zeros((max_a + 1, max_b + 1))
      for i in range(len(a)):
          d[int(a[i]), int(b[i])] += 1
      fig, ax = plt.subplots()
      ax.set_xlim(min_b - 0.5, max_b + 0.5)
      ax.set_ylim(min_a - 0.5, max_a + 0.5)
      ax.invert_yaxis()
      img = ax.matshow(d, cmap="BuGn",)
      fig.colorbar(img)
      plt.show()
  