Irregular matplotlib date x-axis labels?

I currently have date x-axis labels in matplotlib in this format:

'..., Oct 08, Nov 08, Dec 08, Jan 09, Feb开发者_JS百科 09, Mar 09, ...'

Is it possible to only show the year number for January for every year instead?

'..., Oct, Nov, Dec, Jan 09, Feb, Mar, ...'

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Following up on Jouni's answer here's a quick and dirty example:

import matplotlib.pyplot as plt
import matplotlib.ticker as ticker
import random, datetime

# generator to just get 20 dates += 30 days
def nextDate():
      date = datetime.date(2008, 12,01)
      while 1:
        date += datetime.timedelta(days=30)
        yield (date)

nd = nextDate()
some_dates = [nd.next() for i in range(0,20)] #get 20 dates
ys = [random.randint(1,100) for i in range(0,20)] # get dummy y data

plt.plot([i for i in range(0,20)],ys) #plot dummy data

def format_date(x, pos=None):
    date = some_dates[int(x)]
    if date.month == 1: 
      return date.strftime('%b %Y')
    else: return date.strftime('%b')

xAxis = plt.axes().xaxis
xAxis.set_major_locator(ticker.FixedLocator([i for i in range(0,20)])) #show all 20 dates on xaxis
xAxis.set_major_formatter(ticker.FuncFormatter(format_date)) # custom format
for tl in xAxis.get_ticklabels():
      tl.set_fontsize(10)
      tl.set_rotation(30)
      # rotate and pretty up

plt.show()

alt text http://www.imagechicken.com/uploads/1265573633082937000.png

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Use a custom formatter as in this example:

http://matplotlib.sourceforge.net/examples/api/date_index_formatter.html