I am trying to plot some data using matplotlib and pandas. However when using the DateFormatter, dates are being rendered incorrectly depending on what I filter out of the DataFrame:

The dates in the two examples below render with matplotlib as 'August 20 00 2013', as expected:

df['metric2'].plot()
ax = gca()
ax.xaxis.set_major_formatter(DateFormatter('%B %d %H %Y'))
draw()df[df['metric1']>1000]['metric2'].plot()
ax = gca()
ax.xaxis.set_major_formatter(DateFormatter('%B %d %H %Y'))
draw()

However using the code below, the dates are being rendered as 'February 01 00 1048':

df[df['browser']=='Chrome/29']['metric2'].plot()
ax = gca()
ax.xaxis.set_major_formatter(DateFormatter('%B %d %H %Y'))
draw()

We need to have a concrete set of data and a program to refer to. No problems here:

data.txt:

2013-08-18 00   IE  1000    500 3000
2013-08-19 00   FF  2000    250 6000
2013-08-20 00   Opera   3000    450 9000
2001-03-21 00   Chrome/29   3000    450 9000
2013-08-21 00   Chrome/29   3000    450 9000
2014-01-22 00   Chrome/29   3000    750 9000

.

import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.dates as md
import datetime as dtdf = pd.read_table('data.txt', index_col=0, parse_dates=True,date_parser=lambda s: dt.datetime.strptime(s, '%Y-%m-%d %H'),header=None,names=['browser', 'metric1', 'metric2', 'metric3']
)print dfdf[df['browser']=='Chrome/29']['metric2'].plot()
ax = plt.gca()
ax.xaxis.set_major_formatter(md.DateFormatter('%B %d %H %Y'))
plt.draw()
plt.show()--output:--browser  metric1  metric2  metric3
2013-08-18         IE     1000      500     3000
2013-08-19         FF     2000      250     6000
2013-08-20      Opera     3000      450     9000
2001-03-21  Chrome/29     3000      450     9000
2013-08-21  Chrome/29     3000      450     9000
2014-01-22  Chrome/29     3000      750     9000

And with the axes adjusted so you can see the points better(setting date range of x axis, setting range of y axis):

...
df[df['browser']=='Chrome/29']['metric2'].plot(style='r--')
ax = plt.gca()
ax.xaxis.set_major_formatter(md.DateFormatter('%B %d %H %Y'))ax.set_xlim(dt.datetime(2000, 1, 1,), dt.datetime(2017, 1, 1))
ax.set_ylim(400, 1000)
...
...

As long as you refuse to post a minimal example along with the data that produces the output you don't want...