lcmlog-py

LCM log utilities

Installation

lcmlog-py is available on PyPI:

pip install lcmlog-py

Usage

Events

lcmlog-py provides classes to abstract the LCM log file format. The Event class represents a single event in the log file. An Event is composed of a header, channel string, and data byte array.

The Header class represents a fixed-length header at the beginning of each event which describes the event number, timestamp, and channel/data lengths. This is parsed first, and then the channel and data are read in.

If the header is read incorrectly or is corrupt, a BadSyncError is raised.

To read a header, call the Header.from_file method:

from lcmlog import Header

with open('lcmlog', 'rb') as f:
    header = Header.from_file(f)

print(header.timestamp)  # e.g.

A full event can be read via the Event.from_file method:

from lcmlog.event import Event

with open('lcmlog', 'rb') as f:
    event = Event.from_file(f)

print(event.header.timestamp)
print(event.channel)  # e.g.

Log Reader & Writer

lcmlog-py also provides two utility classes for reading and writing LCM log files in order.

The LogReader reads events from a file (starting at the beginning) and the LogWriter writes events to a file. The LogReader class is iterable. Both classes close their respective files when they are garbage collected.

from lcmlog import LogReader, LogWriter

reader = LogReader('lcmlog_source')
writer = LogWriter('lcmlog_dest')

# Read and write each event
for event in reader:
    writer.write(event)