title: Matplotlib: How to plot multiple lines from columns of an array, but give them one label?
body: <p>I would like to plot multiple columns of an array and label them all the same in the plot legend. However when using:</p>
  
  <pre><code>x = np.loadtxt('example_array.npy')
  plt.plot(x[:,1:3],label = 'first 2 lines')
  plt.plot(x[:,3:5],label = '3rd and 4th lines')
  plt.legend()
  </code></pre>
  
  <p>I get as many legend labels as lines I have. So the above code yields four labels in the legend box.</p>
  
  <p>There must be a simple way to assign a label for a group of lines?! But I cannot find it...</p>
  
  <p>I would like to avoid having to resort to</p>
  
  <pre><code>x = np.loadtxt('example_array.npy')
  plt.plot(x[:,1],label = 'first 2 lines')
  plt.plot(x[:,1:3])
  plt.plot(x[:,3],label = '3rd and 4th lines')
  plt.plot(x[:,3:5])
  plt.legend()
  </code></pre>
  
  <p>Thanks in advance</p>