text: #!/usr/bin/env python
  
  import datetime
  from matplotlib.pyplot import figure, show
  from matplotlib.dates import DayLocator, HourLocator, DateFormatter, drange
  from numpy import arange
  
  date1 = datetime.datetime( 2000, 3, 2)
  date2 = datetime.datetime( 2000, 3, 6)
  delta = datetime.timedelta(hours=6)
  dates = drange(date1, date2, delta)
  
  y = arange( len(dates)*1.0)
  
  fig = figure()
  ax = fig.add_subplot(111)
  ax.plot_date(dates, y*y)
  
  # this is superfluous, since the autoscaler should get it right, but
  # use date2num and num2date to convert between dates and floats if
  # you want; both date2num and num2date convert an instance or sequence
  ax.set_xlim( dates[0], dates[-1] )
  
  # The hour locator takes the hour or sequence of hours you want to
  # tick, not the base multiple
  
  ax.xaxis.set_major_locator( DayLocator() )
  ax.xaxis.set_minor_locator( HourLocator(arange(0,25,6)) )
  ax.xaxis.set_major_formatter( DateFormatter('%Y-%m-%d') )
  
  ax.fmt_xdata = DateFormatter('%Y-%m-%d %H:%M:%S')
  fig.autofmt_xdate()
  
  show()
  