Bag Class Reference

Bag factory metaclass. More...

Inheritance diagram for Bag:

Public Member Functions
	__new__ (cls, f, mode="r", reindex=False, progress=False, **kwargs)
	Returns an object for reading or writing ROS bags.
	__subclasshook__ (cls, C)
	autodetect (cls, f)
	Returns registered bag class auto-detected from file, or None.
Public Member Functions inherited from BaseBag
	__bool__ (self)
	__contains__ (self, key)
	Returns whether bag contains given topic.
	__copy__ (self)
	__deepcopy__ (self, memo=None)
	__enter__ (self)
	Context manager entry, opens bag if not open.
	__exit__ (self, exc_type, exc_value, traceback)
	Context manager exit, closes bag.
	__getitem__ (self, key)
	Returns an iterator yielding messages from the bag in given topic, supporting len().
	__iter__ (self)
	Iterates over all messages in the bag.
	__len__ (self)
	Returns the number of messages in the bag.
	__next__ (self)
	Retrieves next message from bag as (topic, message, timestamp).
	__nonzero__ (self)
	__str__ (self)
	Returns informative text for bag, with a full overview of topics and types.
	close (self)
	Closes the bag file.
	flush (self)
	Ensures all changes are written to bag file.
	get_end_time (self)
	Returns the end time of the bag, as UNIX timestamp, or None if bag empty.
	get_message_class (self, typename, typehash=None)
	Returns ROS message type class, or None if unknown message type for bag.
	get_message_count (self, topic_filters=None)
	Returns the number of messages in the bag.
	get_message_definition (self, msg_or_type)
	Returns ROS message type definition full text, including subtype definitions.
	get_message_type_hash (self, msg_or_type)
	Returns ROS message type MD5 hash, or None if unknown message type for bag.
	get_qoses (self, topic, typename)
	Returns topic Quality-of-Service profiles as a list of dicts, or None if not available.
	get_start_time (self)
	Returns the start time of the bag, as UNIX timestamp, or None if bag empty.
	get_topic_info (self, counts=True)
	Returns topic and message type metainfo as {(topic, typename, typehash): count}.
	get_type_and_topic_info (self, topic_filters=None)
	Returns thorough metainfo on topic and message types.
	open (self)
	Opens the bag file if not already open.
	read_messages (self, topics=None, start_time=None, end_time=None, raw=False, **__)
	Yields messages from the bag, optionally filtered by topic and timestamp.
	write (self, topic, msg, t=None, raw=False, **kwargs)
	Writes a message to the bag.

Static Public Attributes
	READER_CLASSES = set()
	Bag reader classes, as {Cls, }.
	WRITER_CLASSES = set()
	Bag writer classes, as {Cls, }.
Static Public Attributes inherited from BaseBag
	BagMessage = collections.namedtuple("BagMessage", "topic message timestamp")
	Returned from read_messages() as (topic name, ROS message, ROS timestamp object).
tuple	MODES = ("r", "w", "a")
	Supported opening modes, overridden in subclasses.
	next
bool	STREAMABLE = True
	Whether bag supports reading or writing stream objects, overridden in subclasses.
	TopicTuple
	Returned from get_type_and_topic_info() as (typename, message count, connection count, median frequency).
	TypesAndTopicsTuple = collections.namedtuple("TypesAndTopicsTuple", ["msg_types", "topics"])
	Returned from get_type_and_topic_info() as ({typename: typehash}, {topic name: TopicTuple}).

Additional Inherited Members
Properties inherited from BaseBag
	closed = property
	Returns whether file is closed.
	filename = property
	Returns bag file path.
	mode = property
	Returns file open mode.
	size = property
	Returns current file size in bytes.
	stop_on_error = property
	Whether raising read error on unknown message type (ROS2 SQLite .db3 specific).
	topics = property
	Returns the list of topics in bag, in alphabetic order.

Detailed Description

Bag factory metaclass.

Result is a format-specific class instance, auto-detected from file extension or content: an extended rosbag.Bag for ROS1 bags, otherwise an object with a conforming interface.

E.g. McapBag if mcap plugin loaded and file recognized as MCAP format.

User plugins can add their own format support to READER_CLASSES and WRITER_CLASSES. Classes can have a static/class method autodetect(filename) returning whether given file is in recognizable format for the plugin class.

Definition at line 381 of file api.py.

Member Function Documentation

__new__()

__new__	(		cls,
			f,
			mode = "r",
			reindex = False,
			progress = False,
		**	kwargs
	)

Returns an object for reading or writing ROS bags.

Suitable Bag class is auto-detected by file extension or content.

Parameters

f	bag file path, or a stream object (streams not supported for ROS2 .db3 SQLite bags)
mode	return reader if "r" else writer
reindex	reindex unindexed bag (ROS1 only), making a backup if indexed format
progress	show progress bar with reindexing status
kwargs	additional keyword arguments for format-specific Bag constructor, like compression for ROS1 bag

Definition at line 401 of file api.py.

__subclasshook__()

__subclasshook__	(		cls,
			C
	)

Definition at line 429 of file api.py.

autodetect()

autodetect	(		cls,
			f
	)

Returns registered bag class auto-detected from file, or None.

Definition at line 420 of file api.py.

Member Data Documentation

READER_CLASSES

READER_CLASSES = set()

static

Bag reader classes, as {Cls, }.

Definition at line 384 of file api.py.

WRITER_CLASSES

WRITER_CLASSES = set()

static

Bag writer classes, as {Cls, }.

Definition at line 387 of file api.py.

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The documentation for this class was generated from the following file:

• grepros/api.py