Client API Tutorial¶
In addition to bag cat and bag play, RSBag provides a simple client API for working with log files. Analyzing, visualizing and transforming recorded data are the primary use-cases for this API.
Preparation¶
See also
- Preparation
- Installing RSBag
This section assumes a working installation of RSBag including at least one of the client APIs.
The RSBag client API for Python is provided by the
rsbag module. To use the module
import rsbag
All subsequent listings assume this.
(ql:quickload '(:cl-rsbag :rsbag-tidelog))
Note
The client API presented here only takes care of making available the contents of log files, not the interpretation of this data. Depending on the kind of data, it may be necessary to load and/or register RSB converters to access the data in a convenient form. See Sending and Receiving Custom Data Types for details.
Opening A Log file¶
Processing data in log files starts with opening the respective log file.
Log files are opened using the
rsbag.openBag() function. This function returns a
Bag object implementing the
context manager protocol:
1 2 3 | with rsbag.openBag('/media/local_data/foo.tide',
channels = [ 'vision' ]) as bag:
pass
|
(rsbag:with-bag (bag "/media/local_data/foo.tide" :direction :input)
(rsbag:bag-channel bag "vision"))
Accessing Events¶
Events are accessed using the
rsbag.Bag.events and rsbag.Bag.items
properties. Both behave like ordinary Python sequences:
1 2 3 4 5 | with rsbag.openBag('/media/local_data/foo.tide',
channels = [ 'vision' ]) as bag:
print len(bag.events)
for e in bag.events:
print (e.scope, e.metaData.createTime, e.data.width, e.data.height)
|
(rsbag:with-bag (bag "/media/local_data/foo.tide" :direction :input)
(values
(length (rsbag:bag-channel bag "vision"))
(subseq (rsbag:bag-channel bag "vision") 5 10)))
