title: numpy only size-1 arrays can be converted to Python scalars
body: <pre><code>import random
  random.randint(0, 255)
  array_xx= np.full((255), random.randint(0, 255))
  array_yy= np.full((255), random.randint(0, 255))
  array_col= np.full((255), random.randint(0, 255))
  plt.plot(array_xx,array_yy, c='#00'+'{:02x}'.format(int(array_col*255),2)+'00')
  plt.show()
  </code></pre>
  
  <p>I'm trying to make plt.plot take color values from array_col, but
  tells me:</p>
  
  <pre><code>only size-1 arrays can be converted to Python scalars
  </code></pre>
  
  <p>How do I fix this?</p>