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How to extract data from *.bag?
I recorded my odomerty and laser data using rosbag. I want to extract (specific) data stream(text format) from recorded bagfiles. (time, step, odometry[x,y,...], laser data, ...) Becuase my unfinshied project are programed by matlab.
Question. 1) How to extract data from *.bag? (using matlab, C/C++ or ROS API...)
convert a bag file to .csv format, use
$ rostopic echo /topicname -b bagFileName.bag -p > file.csv
Remember to replace topicname with your topic (/tactile). And bagFileName.bag need to be replace with your bag file that you need to convert. And finally file.csv will be your output file. Instead of having .csv you can try .txt also. But for the best practice .csv file is good.
Here is a small python framework that extracts bag information from a bag file and puts it in a pandas dataframe in python. It also has two small scripts to dump it into a csv file or place graph information from a topic. https://github.com/aktaylor08/RosbagP...
Hi I have also used the standard way to extract bag data:
rostopic echo -b bag_name.bag -p/topic_desired > name_of_topic.csv
B I used the option:
rosbag record -a
Thus I have recorded about 200 topics of bag data not just one. And it would be very exhaustive type the 1st command above one by one to convert all the 200 topic's data to csv. It there a command or script that I run only once and convert all my topics to different csvs? For example something like this:
rostopic echo -b bag_name.bag -p/ALLTOPICS desired > Separated_topics_filenames.csv
And have:
planning.csv odometry.csv pose.csv etc
I have tried this:
$ rostopic echo -b all_topics_bag.bag -p / current_pose > current_pose.csv
Ok It works and created the csv, then I tried this to get all data
$ rostopic echo -b all_topics_bag.bag -p / current_pose > current_pose.csv ...just type the following in the directory of bag file:
rostopic echo -b bagname.bag -p /topicname > filename.csv
the data will save into filename.csv then you can use it in matlab
Asked: 2011-02-16 18:38:45 -0500
Seen: 95,550 times
Last updated: Oct 11 '20
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Ok, is it possible to extract the contents of the bag file time, step, odometry[x,y..] and write our own customize code in cpp or java to move the robot through particular location of the map. Does we need to create the package with our customize code? How to combine all in built packages of ros and our own package?
The script worked well for me, but I didn't test for a bunch of different bags. I'd imagine it wouldn't work if the bag contains data of a type that is not just a simple number
@changhyun, did you find the relevant solution? I am also trying to retrieve the odom data in terms of each step , data and all. The below "highlighted" answer is not giving me the required output. Did you find the solution? Kindly help