Plot a histogram of mailinglist activity

datehist.py

#!/usr/bin/env python

"""
Plot histogram from list of dates

Usage
=====
Point to mbox file.

Ex.1: plot mailinglist activity::

    datehist.py -t `ubuntu-motu list` ubuntu-motu.mbox

"""

import sys
import time
import datetime
import mailbox
import email.utils
import numpy
from matplotlib import pyplot
from matplotlib.dates import YearLocator, MonthLocator, DateFormatter
from matplotlib.dates import epoch2num, date2num
from optparse import OptionParser


def num_now():
    """
    Return the current date in matplotlib representation
    """
    return date2num(datetime.datetime.now())


def read_dates(filename):
    print filename
    dates = []
    mbox = mailbox.mbox(filename)
    for message in mbox:
        date = message['date']
        foo = email.utils.parsedate(date)
        stamp = time.mktime(foo)
        num = epoch2num(stamp)
        dates.append(num)
    return dates


def plot_datehist(dates, bins, title=None):
    (hist, bin_edges) = numpy.histogram(dates, bins)
    width = bin_edges[1] - bin_edges[0]

    fig = pyplot.figure()
    ax = fig.add_subplot(111)
    ax.bar(bin_edges[:-1], hist / width, width=width)
    ax.set_xlim(bin_edges[0], num_now())
    ax.set_ylabel('Events [1/day]')
    if title:
        ax.set_title(title)

    # set x-ticks in date
    # see: http://matplotlib.sourceforge.net/examples/api/date_demo.html
    ax.xaxis.set_major_locator(YearLocator())
    ax.xaxis.set_major_formatter(DateFormatter('%Y'))
    ax.xaxis.set_minor_locator(MonthLocator())
    # format the coords message box
    ax.format_xdata = DateFormatter('%Y-%m-%d')
    ax.grid(True)

    fig.autofmt_xdate()
    return fig


def main():
    parser = OptionParser(usage='%prog [options] <path/to/mbox>')
    parser.add_option("-o", "--out", default=None,
                      help="output file. open gui if not specified.")
    parser.add_option("-b", "--bins", default=50, type=int,
                      help="number of bins for histogram. (default: 50)")
    parser.add_option("-t", "--title")
    parser.add_option("-d", "--doc", default=False, action="store_true",
                      help="print document")
    (opts, args) = parser.parse_args()

    if len(args) != 1:
        parser.error("You must provide the path to an mbox file.")

    filename = args[0]

    if opts.doc:
        print __doc__
        return

    dates = read_dates(filename)
    fig = plot_datehist(dates, opts.bins, title=opts.title)

    if opts.out:
        fig.savefig(opts.out)
    else:
        pyplot.show()


if __name__ == '__main__':
    main()