# sometimes it is nice to have ticklabels centered. mpl currently

# associates a label with a tick, and the label can be aligned

# 'center', 'left', or 'right' using the horizontal alignment property:

#

#

# for label in ax.xaxis.get_xticklabels():

# label.set_horizontalalignment('right')

#

#

# but this doesn't help center the label between ticks. One solution

# is to "face it". Use the minor ticks to place a tick centered

# between the major ticks. Here is an example that labels the months,

# centered between the ticks

import numpy as np

import matplotlib.cbook as cbook

import matplotlib.dates as dates

import matplotlib.ticker as ticker

import matplotlib.pyplot as plt

# load some financial data; apple's stock price

fh = cbook.get_sample_data('aapl.npy.gz')

try:

# Python3 cannot load python2 .npy files with datetime(object) arrays

# unless the encoding is set to bytes. Hovever this option was

# not added until numpy 1.10 so this example will only work with

# python 2 or with numpy 1.10 and later.

r = np.load(fh, encoding='bytes')

except TypeError:

r = np.load(fh)

fh.close()

r = r[-250:] # get the last 250 days

fig, ax = plt.subplots()

ax.plot(r.date, r.adj_close)

ax.xaxis.set_major_locator(dates.MonthLocator())

ax.xaxis.set_minor_locator(dates.MonthLocator(bymonthday=15))

ax.xaxis.set_major_formatter(ticker.NullFormatter())

ax.xaxis.set_minor_formatter(dates.DateFormatter('%b'))

for tick in ax.xaxis.get_minor_ticks():

tick.tick1line.set_markersize(0)

tick.tick2line.set_markersize(0)

tick.label1.set_horizontalalignment('center')

imid = len(r)//2

ax.set_xlabel(str(r.date[imid].year))

plt.show()