[Matplotlib-users] Format date tick labels

[Jianbao T. <jia...@gm...>]

Hi,

I am having trouble to customize the format of date axis tick labels. Below
is a snippet to demonstrate my problem:
#------------------------------------- code
----------------------------------------------------
# Make an example plot.
fig = figure()
tsta = num2epoch(date2num(datetime.datetime.now()))
tarr = tsta + arange(0, 60*60*0.5, 0.1)                # half hour, dt =
0.1 sec
x = np.array(num2date(epoch2num(tarr)))
nt = len(tarr)
y = randn(nt)

ax = fig.add_subplot(111)
ax.plot(x, y)
fig.canvas.draw()

# Make a formatter instance.
locator = mpl.dates.AutoDateLocator()
formatter = mpl.dates.AutoDateFormatter(locator)

# Customize the scaling.
formatter.scaled = {
    365.0 : '%Y',               # view interval > 356 days
    30. : '%b %Y',             # view interval > 30 days but less than 365
days
    1.0 : '%b %d',             # view interval > 1 day but less than 30 days
    1./24. : '%H:%M',        # view interval > 1 hour but less than 24 hours
    1./24./60. : '%M:%S',  # view interval > 1 min but less than 1 hour
    1./24./60./60. : '%S',   # view interval < 1 min
}

# Apply the formatter and redraw the plot.
ax.get_xaxis().set_major_formatter(formatter)
fig.canvas.draw()
#---------------------------------- end of code
-------------------------------------------------

I listed my expectation about the new scaling above. However, what I got
was simply '%Y' after I applied the formatter. So, how can I make the new
formatter work, please? Thank you very much.

Jianbao