title: Perlin noise in Python's noise library
body: <p>I have a problem with generating Perlin noise for my project. As I wanted to understand how to use library properly, I tried to follow step-by-step this page: <a href="https://medium.com/@yvanscher/playing-with-perlin-noise-generating-realistic-archipelagos-b59f004d8401" rel="nofollow noreferrer">https://medium.com/@yvanscher/playing-with-perlin-noise-generating-realistic-archipelagos-b59f004d8401</a> 
  In first part, there is code:</p>
  
  <pre><code>import noise
  import numpy as np
  from scipy.misc import toimage
  
  shape = (1024,1024)
  scale = 100.0
  octaves = 6
  persistence = 0.5
  lacunarity = 2.0
  
  world = np.zeros(shape)
  for i in range(shape[0]):
      for j in range(shape[1]):
          world[i][j] = noise.pnoise2(i/scale, 
                                      j/scale, 
                                      octaves=octaves, 
                                      persistence=persistence, 
                                      lacunarity=lacunarity, 
                                      repeatx=1024, 
                                      repeaty=1024, 
                                      base=0)
  
  toimage(world).show()
  </code></pre>
  
  <p>I copy-paste it with small change at the end (toimage is obsolete) so I have:</p>
  
  <pre><code>import noise
  import numpy as np
  from PIL import Image
  
  shape = (1024,1024)
  scale = 100
  octaves = 6
  persistence = 0.5
  lacunarity = 2.0
  seed = np.random.randint(0,100)
  
  world = np.zeros(shape)
  for i in range(shape[0]):
      for j in range(shape[1]):
          world[i][j] = noise.pnoise2(i/scale,
                                      j/scale,
                                      octaves=octaves,
                                      persistence=persistence,
                                      lacunarity=lacunarity,
                                      repeatx=1024,
                                      repeaty=1024,
                                      base=seed)
  
  Image.fromarray(world, mode='L').show()
  </code></pre>
  
  <p>I tried a lot of diffrient modes, but this noise is not even close to coherent noise. My result is something like <a href="https://i.stack.imgur.com/eSiib.png" rel="nofollow noreferrer">this</a> (mode='L'). Could someone explain me, what am I doing wrong?  </p>