extract data from bagfile

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I am a new user of ROS. I have produced a bag file with data from Velodyne VLP 16 LIDAR and a GPS. I used a python script from https://www.clearpathrobotics.com/ass... to convert the bag file to csv. But I can't understand the csv file. Can someone explain to me which is x,y,z,intensity ? Or any other way where I could extract LIDAR (timestamp, x,y,z,i), GPS (lat, long)and IMU data (yaw,pitch, roll)? I will be using IMU later.