How can i use xaxis_date() with barh()?

Question

in the code below, bdate and edate are both datetime.datetime() objects:

pylab.barh(ypos, edate - bdate, left=bdate, height=TRMWidth )

but

Answer 1

What's happening is that matplotlib doesn't actually use datetime objects for plotting.

Dates are first converted into an internal floating point format. The conversion isn't set up to handle timedeltas (which is arguably an oversight).

You can basically do exactly what you wanted, you just need to explictly convert the dates to matplotlib's internal format first, and then call ax.xaxis_date().

As a quick example (Most of this is generating data to plot...):

import datetime as dt
import matplotlib.pyplot as plt
import matplotlib.dates as mdates

def drange(start, end, interval=dt.timedelta(days=1)):
    output = []
    while start <= end:
        output.append(start)
        start += interval
    return output

# Generate a series of dates for plotting...
edate = drange(dt.datetime(2012, 2, 1), dt.datetime(2012, 6, 15), 
                      dt.timedelta(days=5))
bdate = drange(dt.datetime(2012, 1, 1), dt.datetime(2012, 5, 15), 
                      dt.timedelta(days=5))

# Now convert them to matplotlib's internal format...
edate, bdate = [mdates.date2num(item) for item in (edate, bdate)]

ypos = range(len(edate))
fig, ax = plt.subplots()

# Plot the data
ax.barh(ypos, edate - bdate, left=bdate, height=0.8, align='center')
ax.axis('tight')

# We need to tell matplotlib that these are dates...
ax.xaxis_date()

plt.show()