apoorva
0c9504b343
git-subtree-dir: rosbags git-subtree-mainline: 48df1fbdf4490f3cbfa3267c998d1a0fc98378ca git-subtree-split: c80625df279c154c6ec069cbac30faa319755e47
71 lines
3.1 KiB
ReStructuredText
71 lines
3.1 KiB
ReStructuredText
Rosbag2
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=======
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The :py:mod:`rosbags.rosbag2` package provides a conformant implementation of rosbag2. It provides read-write access to raw message data saved inside rosbag2 containers, and supports all features present in the C++ reference implementation.
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Supported Versions
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------------------
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All versions up to the current (ROS2 Humble) version 6 are supported.
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Supported Features
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------------------
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Rosbag2 is a flexible format that supports plugging different serialization methods, compression formats, and storage containers together. The rosbag2 C++ reference implementation is build around plugins that provide serialization, compression, and storage. This project implements all rosbag2 core plugins that are distributed with the C++ reference implementation.
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:Serializers:
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- cdr (without wstring)
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:Compressors:
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- zstd
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:Storages:
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- sqlite3
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- mcap
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Writing rosbag2
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---------------
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Instances of the :py:class:`Writer <rosbags.rosbag2.Writer>` class can create and write to new rosbag2 files. It is usually used as a context manager. Before the first message of a topic can be written, its topic must first be added to the bag. The following example shows the typical usage pattern:
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.. code-block:: python
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from rosbags.rosbag2 import Writer
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from rosbags.serde import serialize_cdr
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from rosbags.typesys.types import std_msgs__msg__String as String
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# create writer instance and open for writing
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with Writer('/home/ros/rosbag_2020_03_24') as writer:
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# add new connection
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topic = '/chatter'
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msgtype = String.__msgtype__
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connection = writer.add_connection(topic, msgtype, 'cdr', '')
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# serialize and write message
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timestamp = 42
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message = String('hello world')
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writer.write(connection, timestamp, serialize_cdr(message, msgtype))
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Reading rosbag2
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---------------
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Instances of the :py:class:`Reader <rosbags.rosbag2.Reader>` class are used to read rosbag2 metadata and its contents. Most of the metadata is available on Reader instances right away, messages can only be accessed after the bag has been opened. To this end it is recommended to use the Reader as a context manager. The following example shows the typical usage pattern:
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.. code-block:: python
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from rosbags.rosbag2 import Reader
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from rosbags.serde import deserialize_cdr
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# create reader instance and open for reading
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with Reader('/home/ros/rosbag_2020_03_24') as reader:
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# topic and msgtype information is available on .connections list
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for connection in reader.connections:
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print(connection.topic, connection.msgtype)
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# iterate over messages
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for connection, timestamp, rawdata in reader.messages():
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if connection.topic == '/imu_raw/Imu':
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msg = deserialize_cdr(rawdata, connection.msgtype)
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print(msg.header.frame_id)
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# messages() accepts connection filters
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connections = [x for x in reader.connections if x.topic == '/imu_raw/Imu']
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for connection, timestamp, rawdata in reader.messages(connections=connections):
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msg = deserialize_cdr(rawdata, connection.msgtype)
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print(msg.header.frame_id)
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