openpilot_comma/tools/lib/README.md

## LogReader

Route is a class for conveniently accessing all the [logs](/system/loggerd/) from your routes. The LogReader class reads the non-video logs, i.e. rlog.bz2 and qlog.bz2. There's also a matching FrameReader class for reading the videos.

```python
from openpilot.tools.lib.route import Route
from openpilot.tools.lib.logreader import LogReader

r = Route("a2a0ccea32023010|2023-07-27--13-01-19")

# get a list of paths for the route's rlog files
print(r.log_paths())

# and road camera (fcamera.hevc) files
print(r.camera_paths())

# setup a LogReader to read the route's first rlog
lr = LogReader(r.log_paths()[0])

# print out all the messages in the log
import codecs
codecs.register_error("strict", codecs.backslashreplace_errors)
for msg in lr:
  print(msg)

# setup a LogReader for the route's second qlog
lr = LogReader(r.log_paths()[1])

# print all the steering angles values from the log
for msg in lr:
  if msg.which() == "carState":
    print(msg.carState.steeringAngleDeg)
```

### Segment Ranges

We also support a new format called a "segment range", where you can specify which segments from a route to load.

```python

lr = LogReader("a2a0ccea32023010|2023-07-27--13-01-19/4")   # 4th segment
lr = LogReader("a2a0ccea32023010|2023-07-27--13-01-19/4:6") # 4th and 5th segment
lr = LogReader("a2a0ccea32023010|2023-07-27--13-01-19/-1")  # last segment
lr = LogReader("a2a0ccea32023010|2023-07-27--13-01-19/:5")  # first 5 segments
lr = LogReader("a2a0ccea32023010|2023-07-27--13-01-19/1:")  # all except first segment
```

and can select which type of logs to grab

```python
lr = LogReader("a2a0ccea32023010|2023-07-27--13-01-19/4/q") # get qlogs
lr = LogReader("a2a0ccea32023010|2023-07-27--13-01-19/4/r") # get rlogs (default)
```