Class Bag

Open a bag file. The mode can be 'r', 'w', or 'a' for reading (default), writing or appending. The file will be created if it doesn't exist when opened for writing or appending; it will be truncated when opened for writing. Simultaneous reading and writing is allowed when in writing or appending mode.

Parameters:

• f (str or file) - filename of bag to open or a stream to read from
• mode (str) - mode, either 'r', 'w', or 'a'
• compression (str) - compression mode, see rosbag.Compression for valid modes
• chunk_threshold (int) - minimum number of uncompressed bytes per chunk
• allow_unindexed (bool) - if True, allow opening unindexed bags
• options (dict) - the bag options (currently: compression and chunk_threshold)
• skip_index (bool) - if True, don't read the connection index records on open [2.0+]

Raises:

• ValueError - if any argument is invalid
• ROSBagException - if an error occurs opening file
• ROSBagFormatException - if bag format is corrupted

Overrides: object.__init__

Read messages from the bag, optionally filtered by topic, timestamp and connection details.

Parameters:

• topics (list(str) or str) - list of topics or a single topic. if an empty list is given all topics will be read [optional]
• start_time (genpy.Time) - earliest timestamp of message to return [optional]
• end_time (genpy.Time) - latest timestamp of message to return [optional]
• connection_filter (function taking (topic, datatype, md5sum, msg_def, header) and returning bool) - function to filter connections to include [optional]
• raw (bool) - if True, then generate tuples of (datatype, (data, md5sum, position), pytype)

Returns: generator of tuples of (str, genpy.Message, genpy.Time) [not raw] or (str, (str, str, str, tuple, class), genpy.Time) [raw]

generator of BagMessage(topic, message, timestamp) namedtuples for each message in the bag file

Write the open chunk to disk so subsequent reads will read all messages.

Raises:

• ValueError - if bag is closed

Write a message to the bag.

Parameters:

• topic (str) - name of topic
• msg (Message or tuple of raw message data) - message to add to bag, or tuple (if raw)
• t (genpy.Time) - ROS time of message publication, if None specifed, use current time [optional]
• raw (bool) - if True, msg is in raw format, i.e. (msg_type, serialized_bytes, md5sum, pytype)

Raises:

• ValueError - if arguments are invalid or bag is closed

Reindexes the bag file. Yields position of each chunk for progress.

Close the bag file. Closing an already closed bag does nothing.

Returns information about the compression of the bag

Returns: generator of CompressionTuple of (str, int, int)

generator of CompressionTuple(compression, uncompressed, compressed) describing the type of compression used, size of the uncompressed data in Bytes, size of the compressed data in Bytes. If no compression is used then uncompressed and compressed data will be equal.

Returns the number of messages in the bag. Can be filtered by Topic

Parameters:

• topic_filters (Could be either a single str or a list of str.) - One or more topics to filter by

Returns: int

The number of messages in the bag, optionally filtered by topic

Returns the start time of the bag.

Returns: float, timestamp in seconds, includes fractions of a second

a timestamp of the start of the bag

Returns the end time of the bag.

Returns: float, timestamp in seconds, includes fractions of a second

a timestamp of the end of the bag

Coallates info about the type and topics in the bag.

Note, it would be nice to filter by type as well, but there appear to be some limitations in the current architecture
that prevent that from working when more than one message type is written on the same topic.

@param topic_filters: specify one or more topic to filter by.
@type topic_filters: either a single str or a list of str.
@return: generator of TypesAndTopicsTuple(types{key:type name, val: md5hash}, 
    topics{type: msg type (Ex. "std_msgs/String"),
        message_count: the number of messages of the particular type,
        connections: the number of connections,
        frequency: the data frequency,
        key: type name,
        val: md5hash}) describing the types of messages present
    and information about the topics
@rtype: TypesAndTopicsTuple(dict(str, str), 
    TopicTuple(str, int, int, float, str, str))

str(x)

Overrides: object.__str__

(inherited documentation)

options

Get the options.

Get Method:

unreachable.options(self) - Get the options.

filename

Get the filename.

Get Method:

unreachable.filename(self) - Get the filename.

version

Get the version.

Get Method:

unreachable.version(self) - Get the version.

mode

Get the mode.

Get Method:

unreachable.mode(self) - Get the mode.

size

Get the size in bytes.

Get Method:

unreachable.size(self) - Get the size in bytes.

compression

Get the compression method to use for writing.

Get Method:

_get_compression(self) - Get the compression method to use for writing.

Set Method:

_set_compression(self, compression) - Set the compression method to use for writing.

chunk_threshold

Get the chunk threshold to use for writing.

Get Method:

_get_chunk_threshold(self) - Get the chunk threshold to use for writing.

Set Method:

_set_chunk_threshold(self, chunk_threshold) - Set the chunk threshold to use for writing.