title: Plotting histogram of Pandas Dataframe with its mean and standard deviation, getting ValueError
body: <p>I have a pandas dataframe consisting of daterange as index and one column and 2192 rows. I am able to plot this dataframe on histogram but when I try to include mean and standard deviation of this dataframe on histogram I get a ValueError caused at these lines</p>
  
  <pre><code>#compute daily returns
  daily_returns = stats.compute_daily_returns(df_btc)
  #plotter.plot_data(daily_returns, title="Daily returns", ylabel="Daily returns")
  print daily_returns.head()
  
  daily_returns.replace(to_replace=np.inf, value=np.NaN, inplace=True)
  # Plot a histogram
  daily_returns.hist(bins=21)
  plt.show()
  
  # Get mean as standard deviation
  mean = daily_returns.mean()
  std = daily_returns.std()
  
  print mean
  print std
  
  #the problem comes here  
  plt.axvline(mean, color='w', linestyle='dashed', linewidth=2)
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/GWTQU.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/GWTQU.png" alt="enter image description here"></a></p>
  
  <p>The error is in dataextract.py of my repository on <a href="https://github.com/harindersingh/MachineLearningUsingPython" rel="nofollow noreferrer">github</a></p>
  
  <p>I have gone through this <a href="https://github.com/JosPolfliet/pandas-profiling/issues/" rel="nofollow noreferrer">link</a> too but it didn't solve my problem</p>