content: # -*- coding: utf-8 -*-
  """
  Created on Sun May 06 05:32:15 2012
  
  Author: Josef Perktold
  editted by: Paul Hobson (2012-08-19)
  """
  from scipy import stats
  from matplotlib import pyplot as plt
  import statsmodels.api as sm
  
  #example from docstring
  data = sm.datasets.longley.load()
  data.exog = sm.add_constant(data.exog, prepend=True)
  mod_fit = sm.OLS(data.endog, data.exog).fit()
  res = mod_fit.resid
  
  left = -1.8   #x coordinate for text insert
  
  fig = plt.figure()
  
  ax = fig.add_subplot(2, 2, 1)
  sm.graphics.qqplot(res, ax=ax)
  top = ax.get_ylim()[1] * 0.75
  txt = ax.text(left, top, 'no keywords', verticalalignment='top')
  txt.set_bbox(dict(facecolor='k', alpha=0.1))
  
  ax = fig.add_subplot(2, 2, 2)
  sm.graphics.qqplot(res, line='s', ax=ax)
  top = ax.get_ylim()[1] * 0.75
  txt = ax.text(left, top, "line='s'", verticalalignment='top')
  txt.set_bbox(dict(facecolor='k', alpha=0.1))
  
  ax = fig.add_subplot(2, 2, 3)
  sm.graphics.qqplot(res, line='45', fit=True, ax=ax)
  ax.set_xlim(-2, 2)
  top = ax.get_ylim()[1] * 0.75
  txt = ax.text(left, top, "line='45', \nfit=True", verticalalignment='top')
  txt.set_bbox(dict(facecolor='k', alpha=0.1))
  
  ax = fig.add_subplot(2, 2, 4)
  sm.graphics.qqplot(res, dist=stats.t, line='45', fit=True, ax=ax)
  ax.set_xlim(-2, 2)
  top = ax.get_ylim()[1] * 0.75
  txt = ax.text(left, top, "dist=stats.t, \nline='45', \nfit=True",
                verticalalignment='top')
  txt.set_bbox(dict(facecolor='k', alpha=0.1))
  
  fig.tight_layout()
  
  plt.gcf()
  
  
  # example with the new ProbPlot class
  import numpy as np
  x = np.random.normal(loc=8.25, scale=3.5, size=37)
  y = np.random.normal(loc=8.00, scale=3.25, size=37)
  pp_x = sm.ProbPlot(x, fit=True)
  pp_y = sm.ProbPlot(y, fit=True)
  
  # probability of exceedance
  fig2 = pp_x.probplot(exceed=True)
  
  # compare x quantiles to y quantiles
  fig3 = pp_x.qqplot(other=pp_y, line='45')
  
  # same as above with probabilities/percentiles
  fig4 = pp_x.ppplot(other=pp_y, line='45')
  