title: matplotlib: histogram and bin labels
body: <p>I'm trying to plot a histogram with bar chart, and I'm having difficulties figuring out how to align the x-axis labels with the actual bins. The code below generates the following plot: <img src="https://i.stack.imgur.com/1MF1e.png" alt="Bar chart"></p>
  
  <p>as you can see, the end of each x-label is not aligned to the center of its bin.  The way i'm thinking about this is: when i apply a 45-degree rotation, the label pivots around its geometrical center.  I was wondering if it's possible to move the pivot up to the top of the label. (Or simply translate all the labels slightly left.)</p>
  
  <pre><code>import matplotlib.pyplot as plt
  import numpy as np
  
  #data
  np.random.seed(42)
  data = np.random.rand(5)
  names = ['A:GBC_1233','C:WERT_423','A:LYD_342','B:SFS_23','D:KDE_2342']
  
  ax = plt.subplot(111)
  width=0.3
  bins = map(lambda x: x-width/2,range(1,len(data)+1))
  ax.bar(bins,data,width=width)
  ax.set_xticks(map(lambda x: x, range(1,len(data)+1)))
  ax.set_xticklabels(names,rotation=45)
  
  plt.show()
  </code></pre>