Script for plotting rosbag topics. Depends on pybag.

plot_bag.py

#!/usr/bin/env python

import sys
import pybag

import matplotlib.pyplot as plt

def initialize_plot(num_fields):
    config = {}
    config['fig'] = plt.figure()
    config['num_fields'] = num_fields
    return config

def add_plot(config, index, time, data, name):
    plt.subplot(config['num_fields'], 1, index+1)
    if type(data[0]) is tuple:
        pass
    else:
        plt.plot(time, data)
        plt.title(name)

def finalize_plot(config):
    plt.show(block=False)

def dig(obj, name, time):
    # if obj is a list of scalars or tuples, plot
    if type(obj) is list:
        if type(obj[0]) is tuple:
            print 'Plotting tuple %s' % (name)
            size = len(obj[0])
            config = initialize_plot(size)
            for i in xrange(size):
                add_plot(config, i, time, [obj[t][i] for t in xrange(len(obj))], "%s[%d]" % (name, i))
            finalize_plot(config)
        elif isinstance(obj[0], (int,float)):
            print 'Plotting scalar %s' % (name)
            config = initialize_plot(1)
            add_plot(config, 0, time, obj, name)
            finalize_plot(config)

    # if obj is a dict, dig deeper
    elif type(obj) is dict:
        # if there's only one, recurse in
        if len(obj.keys()) is 1:
            dig(obj[obj.keys()[0]], name + '.' + obj.keys()[0], time)
            return

        # if all keys map to lists of scalars, plot them in subplots
        scalars = True
        for k,v in obj.iteritems():
            if not (type(v) is list and isinstance(v[0], (int,float))):
                scalars = False
                break
        if scalars:
            config = initialize_plot(len(obj.keys()))
            for k,v in obj.iteritems():
                print 'Plotting %s' % (name + '.' + k)
            for i,k in enumerate(obj.keys()):
                add_plot(config, i, time, obj[k], name + '.' + k)
            finalize_plot(config)
            return

        # otherwise keep digging
        print 'Select a field:'
        for index, key in enumerate(obj.keys()):
            print '\t%2d: %s' % (index, key)
        valid = False
        while not valid:
            selection = input('Enter index: ')
            valid = selection in xrange(len(obj.keys()))
        dig(obj[obj.keys()[selection]], name + '.' + obj.keys()[selection], time)
    else:
        print 'Error: unsupported type %s' % (type(obj))

bag_file = sys.argv[1]

print 'Loading bag file...'
bag = pybag.PyBag(bag_file)
data = bag.data()
print 'Done.'

topics = bag.topics()
start_time = bag.start_time()

done = False
while not done:
    print '=' * 60
    print 'Select a topic:'
    for index, topic in enumerate(topics):
        print '\t%2d: %s' % (index, topic)
    valid = False
    while not valid:
        selection = input('Enter index or -1 to quit: ')
        if selection == -1:
            sys.exit()
        valid = selection in xrange(len(topics))

    name = topics[selection]
    current = data[bag.topic_to_field(topics[selection])]
    dig(current, name, current['__time__'])

Where do I find pybag?