diff --git a/list_topic_didiset2.out b/list_topic_didiset2.out
new file mode 100644
index 0000000..9bcc299
--- /dev/null
+++ b/list_topic_didiset2.out
@@ -0,0 +1,628 @@
+lenovo@lenovo-Default-string:~/didi/DiDi-Udacity-Data-Reader$ python list_topics.py 
+[ 1.bag ]
+  /can_bus_dbw/can_rx => 39981
+  /cloud_nodelet/parameter_descriptions => 1
+  /cloud_nodelet/parameter_updates => 1
+  /diagnostics => 561
+  /diagnostics_agg => 169
+  /diagnostics_toplevel_state => 169
+  /image_raw => 1353
+  /objects/capture_vehicle/front/gps/fix => 444
+  /objects/capture_vehicle/front/gps/rtkfix => 564
+  /objects/capture_vehicle/front/gps/time => 537
+  /objects/capture_vehicle/rear/gps/fix => 94
+  /objects/capture_vehicle/rear/gps/rtkfix => 564
+  /objects/capture_vehicle/rear/gps/time => 399
+  /objects/obs1/rear/gps/fix => 66
+  /objects/obs1/rear/gps/rtkfix => 564
+  /objects/obs1/rear/gps/time => 388
+  /radar/points => 1128
+  /radar/range => 1128
+  /radar/tracks => 1129
+  /rosout => 29
+  /vehicle/brake_info_report => 2820
+  /vehicle/brake_report => 2816
+  /vehicle/dbw_enabled => 1
+  /vehicle/filtered_accel => 2814
+  /vehicle/fuel_level_report => 564
+  /vehicle/gear_report => 1126
+  /vehicle/gps/fix => 57
+  /vehicle/gps/time => 57
+  /vehicle/gps/vel => 57
+  /vehicle/imu/data_raw => 5627
+  /vehicle/joint_states => 8457
+  /vehicle/misc_1_report => 1125
+  /vehicle/sonar_cloud => 280
+  /vehicle/steering_report => 2814
+  /vehicle/surround_report => 280
+  /vehicle/suspension_report => 2820
+  /vehicle/throttle_info_report => 5637
+  /vehicle/throttle_report => 2815
+  /vehicle/tire_pressure_report => 113
+  /vehicle/twist => 2815
+  /vehicle/twist_controller/parameter_descriptions => 1
+  /vehicle/twist_controller/parameter_updates => 1
+  /vehicle/wheel_speed_report => 5637
+  /velodyne_nodelet_manager/bond => 224
+  /velodyne_packets => 564
+Total: 98791
+
+[ 11_f.bag ]
+  /can_bus_dbw/can_rx => 29067
+  /cloud_nodelet/parameter_descriptions => 1
+  /cloud_nodelet/parameter_updates => 1
+  /diagnostics => 407
+  /diagnostics_agg => 122
+  /diagnostics_toplevel_state => 122
+  /image_raw => 984
+  /objects/capture_vehicle/front/gps/fix => 329
+  /objects/capture_vehicle/front/gps/rtkfix => 410
+  /objects/capture_vehicle/front/gps/time => 394
+  /objects/capture_vehicle/rear/gps/fix => 69
+  /objects/capture_vehicle/rear/gps/rtkfix => 410
+  /objects/capture_vehicle/rear/gps/time => 288
+  /objects/obs1/rear/gps/fix => 85
+  /objects/obs1/rear/gps/rtkfix => 389
+  /objects/obs1/rear/gps/time => 293
+  /radar/points => 819
+  /radar/range => 820
+  /radar/tracks => 820
+  /rosout => 29
+  /vehicle/brake_info_report => 2052
+  /vehicle/brake_report => 2048
+  /vehicle/dbw_enabled => 1
+  /vehicle/filtered_accel => 2046
+  /vehicle/fuel_level_report => 410
+  /vehicle/gear_report => 819
+  /vehicle/gps/fix => 41
+  /vehicle/gps/time => 41
+  /vehicle/gps/vel => 41
+  /vehicle/imu/data_raw => 4093
+  /vehicle/joint_states => 6153
+  /vehicle/misc_1_report => 818
+  /vehicle/sonar_cloud => 207
+  /vehicle/steering_report => 2046
+  /vehicle/surround_report => 207
+  /vehicle/suspension_report => 2052
+  /vehicle/throttle_info_report => 4099
+  /vehicle/throttle_report => 2048
+  /vehicle/tire_pressure_report => 82
+  /vehicle/twist => 2048
+  /vehicle/twist_controller/parameter_descriptions => 1
+  /vehicle/twist_controller/parameter_updates => 1
+  /vehicle/wheel_speed_report => 4099
+  /velodyne_nodelet_manager/bond => 164
+  /velodyne_packets => 410
+Total: 71886
+
+[ 12_f.bag ]
+  /can_bus_dbw/can_rx => 55343
+  /cloud_nodelet/parameter_descriptions => 1
+  /cloud_nodelet/parameter_updates => 1
+  /diagnostics => 774
+  /diagnostics_agg => 234
+  /diagnostics_toplevel_state => 234
+  /image_raw => 1873
+  /objects/capture_vehicle/front/gps/fix => 569
+  /objects/capture_vehicle/front/gps/rtkfix => 780
+  /objects/capture_vehicle/front/gps/time => 737
+  /objects/capture_vehicle/rear/gps/fix => 101
+  /objects/capture_vehicle/rear/gps/rtkfix => 780
+  /objects/capture_vehicle/rear/gps/time => 551
+  /objects/obs1/rear/gps/fix => 126
+  /objects/obs1/rear/gps/rtkfix => 734
+  /objects/obs1/rear/gps/time => 536
+  /radar/points => 1560
+  /radar/range => 1561
+  /radar/tracks => 1561
+  /rosout => 29
+  /vehicle/brake_info_report => 3904
+  /vehicle/brake_report => 3898
+  /vehicle/dbw_enabled => 1
+  /vehicle/filtered_accel => 3895
+  /vehicle/fuel_level_report => 780
+  /vehicle/gear_report => 1559
+  /vehicle/gps/fix => 78
+  /vehicle/gps/time => 78
+  /vehicle/gps/vel => 78
+  /vehicle/imu/data_raw => 7788
+  /vehicle/joint_states => 11706
+  /vehicle/misc_1_report => 1558
+  /vehicle/sonar_cloud => 393
+  /vehicle/steering_report => 3895
+  /vehicle/surround_report => 393
+  /vehicle/suspension_report => 3904
+  /vehicle/throttle_info_report => 7804
+  /vehicle/throttle_report => 3897
+  /vehicle/tire_pressure_report => 156
+  /vehicle/twist => 3898
+  /vehicle/twist_controller/parameter_descriptions => 1
+  /vehicle/twist_controller/parameter_updates => 1
+  /vehicle/wheel_speed_report => 7804
+  /velodyne_nodelet_manager/bond => 312
+  /velodyne_packets => 780
+Total: 136646
+
+[ 13.bag ]
+^CTraceback (most recent call last):
+  File "list_topics.py", line 16, in <module>
+    bag = rosbag.Bag(file)
+  File "/opt/ros/indigo/lib/python2.7/dist-packages/rosbag/bag.py", line 173, in __init__
+    self._open(f, mode, allow_unindexed)
+  File "/opt/ros/indigo/lib/python2.7/dist-packages/rosbag/bag.py", line 1096, in _open
+    if   mode == 'r': self._open_read(f, allow_unindexed)
+  File "/opt/ros/indigo/lib/python2.7/dist-packages/rosbag/bag.py", line 1132, in _open_read
+    self._reader.start_reading()
+  File "/opt/ros/indigo/lib/python2.7/dist-packages/rosbag/bag.py", line 2303, in start_reading
+    self._read_connection_index_records()
+  File "/opt/ros/indigo/lib/python2.7/dist-packages/rosbag/bag.py", line 2311, in _read_connection_index_records
+    _skip_record(self.bag._file)
+  File "/opt/ros/indigo/lib/python2.7/dist-packages/rosbag/bag.py", line 1601, in _skip_record
+    _skip_sized(f)  # skip data
+  File "/opt/ros/indigo/lib/python2.7/dist-packages/rosbag/bag.py", line 1605, in _skip_sized
+    f.seek(size, os.SEEK_CUR)
+KeyboardInterrupt
+lenovo@lenovo-Default-string:~/didi/DiDi-Udacity-Data-Reader$ python list_topics.py 
+[ 1.bag ]
+  /can_bus_dbw/can_rx => 39981
+  /cloud_nodelet/parameter_descriptions => 1
+  /cloud_nodelet/parameter_updates => 1
+  /diagnostics => 561
+  /diagnostics_agg => 169
+  /diagnostics_toplevel_state => 169
+  /image_raw => 1353
+  /objects/capture_vehicle/front/gps/fix => 444
+  /objects/capture_vehicle/front/gps/rtkfix => 564
+  /objects/capture_vehicle/front/gps/time => 537
+  /objects/capture_vehicle/rear/gps/fix => 94
+  /objects/capture_vehicle/rear/gps/rtkfix => 564
+  /objects/capture_vehicle/rear/gps/time => 399
+  /objects/obs1/rear/gps/fix => 66
+  /objects/obs1/rear/gps/rtkfix => 564
+  /objects/obs1/rear/gps/time => 388
+  /radar/points => 1128
+  /radar/range => 1128
+  /radar/tracks => 1129
+  /rosout => 29
+  /vehicle/brake_info_report => 2820
+  /vehicle/brake_report => 2816
+  /vehicle/dbw_enabled => 1
+  /vehicle/filtered_accel => 2814
+  /vehicle/fuel_level_report => 564
+  /vehicle/gear_report => 1126
+  /vehicle/gps/fix => 57
+  /vehicle/gps/time => 57
+  /vehicle/gps/vel => 57
+  /vehicle/imu/data_raw => 5627
+  /vehicle/joint_states => 8457
+  /vehicle/misc_1_report => 1125
+  /vehicle/sonar_cloud => 280
+  /vehicle/steering_report => 2814
+  /vehicle/surround_report => 280
+  /vehicle/suspension_report => 2820
+  /vehicle/throttle_info_report => 5637
+  /vehicle/throttle_report => 2815
+  /vehicle/tire_pressure_report => 113
+  /vehicle/twist => 2815
+  /vehicle/twist_controller/parameter_descriptions => 1
+  /vehicle/twist_controller/parameter_updates => 1
+  /vehicle/wheel_speed_report => 5637
+  /velodyne_nodelet_manager/bond => 224
+  /velodyne_packets => 564
+Total: 98791
+
+[ 11_f.bag ]
+  /can_bus_dbw/can_rx => 29067
+  /cloud_nodelet/parameter_descriptions => 1
+  /cloud_nodelet/parameter_updates => 1
+  /diagnostics => 407
+  /diagnostics_agg => 122
+  /diagnostics_toplevel_state => 122
+  /image_raw => 984
+  /objects/capture_vehicle/front/gps/fix => 329
+  /objects/capture_vehicle/front/gps/rtkfix => 410
+  /objects/capture_vehicle/front/gps/time => 394
+  /objects/capture_vehicle/rear/gps/fix => 69
+  /objects/capture_vehicle/rear/gps/rtkfix => 410
+  /objects/capture_vehicle/rear/gps/time => 288
+  /objects/obs1/rear/gps/fix => 85
+  /objects/obs1/rear/gps/rtkfix => 389
+  /objects/obs1/rear/gps/time => 293
+  /radar/points => 819
+  /radar/range => 820
+  /radar/tracks => 820
+  /rosout => 29
+  /vehicle/brake_info_report => 2052
+  /vehicle/brake_report => 2048
+  /vehicle/dbw_enabled => 1
+  /vehicle/filtered_accel => 2046
+  /vehicle/fuel_level_report => 410
+  /vehicle/gear_report => 819
+  /vehicle/gps/fix => 41
+  /vehicle/gps/time => 41
+  /vehicle/gps/vel => 41
+  /vehicle/imu/data_raw => 4093
+  /vehicle/joint_states => 6153
+  /vehicle/misc_1_report => 818
+  /vehicle/sonar_cloud => 207
+  /vehicle/steering_report => 2046
+  /vehicle/surround_report => 207
+  /vehicle/suspension_report => 2052
+  /vehicle/throttle_info_report => 4099
+  /vehicle/throttle_report => 2048
+  /vehicle/tire_pressure_report => 82
+  /vehicle/twist => 2048
+  /vehicle/twist_controller/parameter_descriptions => 1
+  /vehicle/twist_controller/parameter_updates => 1
+  /vehicle/wheel_speed_report => 4099
+  /velodyne_nodelet_manager/bond => 164
+  /velodyne_packets => 410
+Total: 71886
+
+[ 12_f.bag ]
+  /can_bus_dbw/can_rx => 55343
+  /cloud_nodelet/parameter_descriptions => 1
+  /cloud_nodelet/parameter_updates => 1
+  /diagnostics => 774
+  /diagnostics_agg => 234
+  /diagnostics_toplevel_state => 234
+  /image_raw => 1873
+  /objects/capture_vehicle/front/gps/fix => 569
+  /objects/capture_vehicle/front/gps/rtkfix => 780
+  /objects/capture_vehicle/front/gps/time => 737
+  /objects/capture_vehicle/rear/gps/fix => 101
+  /objects/capture_vehicle/rear/gps/rtkfix => 780
+  /objects/capture_vehicle/rear/gps/time => 551
+  /objects/obs1/rear/gps/fix => 126
+  /objects/obs1/rear/gps/rtkfix => 734
+  /objects/obs1/rear/gps/time => 536
+  /radar/points => 1560
+  /radar/range => 1561
+  /radar/tracks => 1561
+  /rosout => 29
+  /vehicle/brake_info_report => 3904
+  /vehicle/brake_report => 3898
+  /vehicle/dbw_enabled => 1
+  /vehicle/filtered_accel => 3895
+  /vehicle/fuel_level_report => 780
+  /vehicle/gear_report => 1559
+  /vehicle/gps/fix => 78
+  /vehicle/gps/time => 78
+  /vehicle/gps/vel => 78
+  /vehicle/imu/data_raw => 7788
+  /vehicle/joint_states => 11706
+  /vehicle/misc_1_report => 1558
+  /vehicle/sonar_cloud => 393
+  /vehicle/steering_report => 3895
+  /vehicle/surround_report => 393
+  /vehicle/suspension_report => 3904
+  /vehicle/throttle_info_report => 7804
+  /vehicle/throttle_report => 3897
+  /vehicle/tire_pressure_report => 156
+  /vehicle/twist => 3898
+  /vehicle/twist_controller/parameter_descriptions => 1
+  /vehicle/twist_controller/parameter_updates => 1
+  /vehicle/wheel_speed_report => 7804
+  /velodyne_nodelet_manager/bond => 312
+  /velodyne_packets => 780
+Total: 136646
+
+[ 13.bag ]
+  /can_bus_dbw/can_rx => 7076
+  /cloud_nodelet/parameter_descriptions => 1
+  /cloud_nodelet/parameter_updates => 1
+  /diagnostics => 100
+  /diagnostics_agg => 30
+  /diagnostics_toplevel_state => 31
+  /image_raw => 243
+  /objects/capture_vehicle/front/gps/fix => 81
+  /objects/capture_vehicle/front/gps/rtkfix => 100
+  /objects/capture_vehicle/front/gps/time => 99
+  /objects/capture_vehicle/rear/gps/fix => 16
+  /objects/capture_vehicle/rear/gps/rtkfix => 101
+  /objects/capture_vehicle/rear/gps/time => 73
+  /objects/obs1/rear/gps/fix => 12
+  /objects/obs1/rear/gps/rtkfix => 101
+  /objects/obs1/rear/gps/time => 71
+  /radar/points => 199
+  /radar/range => 202
+  /radar/tracks => 202
+  /rosout => 29
+  /vehicle/brake_info_report => 506
+  /vehicle/brake_report => 505
+  /vehicle/dbw_enabled => 1
+  /vehicle/filtered_accel => 503
+  /vehicle/fuel_level_report => 101
+  /vehicle/gear_report => 202
+  /vehicle/gps/fix => 10
+  /vehicle/gps/time => 10
+  /vehicle/gps/vel => 10
+  /vehicle/imu/data_raw => 1008
+  /vehicle/joint_states => 1518
+  /vehicle/misc_1_report => 200
+  /vehicle/sonar_cloud => 51
+  /vehicle/steering_report => 503
+  /vehicle/surround_report => 51
+  /vehicle/suspension_report => 507
+  /vehicle/throttle_info_report => 997
+  /vehicle/throttle_report => 505
+  /vehicle/tire_pressure_report => 21
+  /vehicle/twist => 505
+  /vehicle/twist_controller/parameter_descriptions => 1
+  /vehicle/twist_controller/parameter_updates => 1
+  /vehicle/wheel_speed_report => 1009
+  /velodyne_nodelet_manager/bond => 42
+  /velodyne_packets => 101
+Total: 17636
+
+[ 14_f.bag ]
+  /can_bus_dbw/can_rx => 3183
+  /diagnostics => 40
+  /diagnostics_agg => 20
+  /diagnostics_toplevel_state => 13
+  /image_raw => 108
+  /objects/capture_vehicle/front/gps/fix => 37
+  /objects/capture_vehicle/front/gps/rtkfix => 45
+  /objects/capture_vehicle/front/gps/time => 44
+  /objects/capture_vehicle/rear/gps/fix => 6
+  /objects/capture_vehicle/rear/gps/rtkfix => 45
+  /objects/capture_vehicle/rear/gps/time => 29
+  /objects/obs1/rear/gps/fix => 9
+  /objects/obs1/rear/gps/rtkfix => 45
+  /objects/obs1/rear/gps/time => 34
+  /radar/points => 90
+  /radar/range => 90
+  /radar/tracks => 90
+  /vehicle/brake_info_report => 225
+  /vehicle/brake_report => 224
+  /vehicle/filtered_accel => 224
+  /vehicle/fuel_level_report => 45
+  /vehicle/gear_report => 89
+  /vehicle/gps/fix => 5
+  /vehicle/gps/time => 5
+  /vehicle/gps/vel => 5
+  /vehicle/imu/data_raw => 447
+  /vehicle/joint_states => 672
+  /vehicle/misc_1_report => 90
+  /vehicle/sonar_cloud => 22
+  /vehicle/steering_report => 224
+  /vehicle/surround_report => 22
+  /vehicle/suspension_report => 224
+  /vehicle/throttle_info_report => 448
+  /vehicle/throttle_report => 224
+  /vehicle/tire_pressure_report => 9
+  /vehicle/twist => 224
+  /vehicle/wheel_speed_report => 448
+  /velodyne_nodelet_manager/bond => 16
+  /velodyne_packets => 45
+Total: 7865
+
+[ 17.bag ]
+  /can_bus_dbw/can_rx => 15910
+  /cloud_nodelet/parameter_descriptions => 1
+  /cloud_nodelet/parameter_updates => 1
+  /diagnostics => 219
+  /diagnostics_agg => 66
+  /diagnostics_toplevel_state => 66
+  /image_raw => 539
+  /objects/capture_vehicle/front/gps/fix => 178
+  /objects/capture_vehicle/front/gps/rtkfix => 224
+  /objects/capture_vehicle/front/gps/time => 217
+  /objects/capture_vehicle/rear/gps/fix => 29
+  /objects/capture_vehicle/rear/gps/rtkfix => 225
+  /objects/capture_vehicle/rear/gps/time => 153
+  /objects/obs1/rear/gps/fix => 24
+  /objects/obs1/rear/gps/rtkfix => 213
+  /objects/obs1/rear/gps/time => 149
+  /radar/points => 449
+  /radar/range => 450
+  /radar/tracks => 450
+  /rosout => 29
+  /vehicle/brake_info_report => 1123
+  /vehicle/brake_report => 1122
+  /vehicle/dbw_enabled => 1
+  /vehicle/filtered_accel => 1120
+  /vehicle/fuel_level_report => 225
+  /vehicle/gear_report => 449
+  /vehicle/gps/fix => 23
+  /vehicle/gps/time => 23
+  /vehicle/gps/vel => 23
+  /vehicle/imu/data_raw => 2241
+  /vehicle/joint_states => 3370
+  /vehicle/misc_1_report => 448
+  /vehicle/sonar_cloud => 115
+  /vehicle/steering_report => 1120
+  /vehicle/surround_report => 115
+  /vehicle/suspension_report => 1124
+  /vehicle/throttle_info_report => 2242
+  /vehicle/throttle_report => 1122
+  /vehicle/tire_pressure_report => 45
+  /vehicle/twist => 1121
+  /vehicle/twist_controller/parameter_descriptions => 1
+  /vehicle/twist_controller/parameter_updates => 1
+  /vehicle/wheel_speed_report => 2244
+  /velodyne_nodelet_manager/bond => 88
+  /velodyne_packets => 224
+Total: 39322
+
+[ 2.bag ]
+  /can_bus_dbw/can_rx => 12421
+  /cloud_nodelet/parameter_descriptions => 1
+  /cloud_nodelet/parameter_updates => 1
+  /diagnostics => 171
+  /diagnostics_agg => 53
+  /diagnostics_toplevel_state => 53
+  /image_raw => 424
+  /objects/capture_vehicle/front/gps/fix => 141
+  /objects/capture_vehicle/front/gps/rtkfix => 175
+  /objects/capture_vehicle/front/gps/time => 171
+  /objects/capture_vehicle/rear/gps/fix => 32
+  /objects/capture_vehicle/rear/gps/rtkfix => 177
+  /objects/capture_vehicle/rear/gps/time => 125
+  /objects/obs1/rear/gps/fix => 24
+  /objects/obs1/rear/gps/rtkfix => 177
+  /objects/obs1/rear/gps/time => 118
+  /radar/points => 351
+  /radar/range => 353
+  /radar/tracks => 354
+  /rosout => 29
+  /vehicle/brake_info_report => 883
+  /vehicle/brake_report => 882
+  /vehicle/dbw_enabled => 1
+  /vehicle/filtered_accel => 874
+  /vehicle/fuel_level_report => 176
+  /vehicle/gear_report => 353
+  /vehicle/gps/fix => 18
+  /vehicle/gps/time => 18
+  /vehicle/gps/vel => 18
+  /vehicle/imu/data_raw => 1761
+  /vehicle/joint_states => 2648
+  /vehicle/misc_1_report => 350
+  /vehicle/sonar_cloud => 88
+  /vehicle/steering_report => 874
+  /vehicle/surround_report => 88
+  /vehicle/suspension_report => 883
+  /vehicle/throttle_info_report => 1751
+  /vehicle/throttle_report => 881
+  /vehicle/tire_pressure_report => 35
+  /vehicle/twist => 881
+  /vehicle/twist_controller/parameter_descriptions => 1
+  /vehicle/twist_controller/parameter_updates => 1
+  /vehicle/wheel_speed_report => 1751
+  /velodyne_nodelet_manager/bond => 68
+  /velodyne_packets => 176
+Total: 30811
+
+[ 3_f.bag ]
+  /can_bus_dbw/can_rx => 15136
+  /cloud_nodelet/parameter_descriptions => 1
+  /cloud_nodelet/parameter_updates => 1
+  /diagnostics => 216
+  /diagnostics_agg => 64
+  /diagnostics_toplevel_state => 64
+  /image_raw => 513
+  /objects/capture_vehicle/front/gps/fix => 169
+  /objects/capture_vehicle/front/gps/rtkfix => 213
+  /objects/capture_vehicle/front/gps/time => 203
+  /objects/capture_vehicle/rear/gps/fix => 43
+  /objects/capture_vehicle/rear/gps/rtkfix => 214
+  /objects/capture_vehicle/rear/gps/time => 151
+  /objects/obs1/rear/gps/fix => 22
+  /objects/obs1/rear/gps/rtkfix => 203
+  /objects/obs1/rear/gps/time => 149
+  /radar/points => 427
+  /radar/range => 428
+  /radar/tracks => 428
+  /rosout => 29
+  /vehicle/brake_info_report => 1069
+  /vehicle/brake_report => 1068
+  /vehicle/dbw_enabled => 1
+  /vehicle/filtered_accel => 1066
+  /vehicle/fuel_level_report => 214
+  /vehicle/gear_report => 427
+  /vehicle/gps/fix => 21
+  /vehicle/gps/time => 21
+  /vehicle/gps/vel => 21
+  /vehicle/imu/data_raw => 2133
+  /vehicle/joint_states => 3208
+  /vehicle/misc_1_report => 426
+  /vehicle/sonar_cloud => 106
+  /vehicle/steering_report => 1066
+  /vehicle/surround_report => 106
+  /vehicle/suspension_report => 1069
+  /vehicle/throttle_info_report => 2134
+  /vehicle/throttle_report => 1067
+  /vehicle/tire_pressure_report => 43
+  /vehicle/twist => 1068
+  /vehicle/twist_controller/parameter_descriptions => 1
+  /vehicle/twist_controller/parameter_updates => 1
+  /vehicle/wheel_speed_report => 2136
+  /velodyne_nodelet_manager/bond => 86
+  /velodyne_packets => 214
+Total: 37446
+
+[ 6_f.bag ]
+  /can_bus_dbw/can_rx => 4851
+  /diagnostics => 64
+  /diagnostics_agg => 20
+  /diagnostics_toplevel_state => 20
+  /image_raw => 164
+  /objects/capture_vehicle/front/gps/fix => 58
+  /objects/capture_vehicle/front/gps/rtkfix => 69
+  /objects/capture_vehicle/front/gps/time => 66
+  /objects/capture_vehicle/rear/gps/fix => 14
+  /objects/capture_vehicle/rear/gps/rtkfix => 69
+  /objects/capture_vehicle/rear/gps/time => 45
+  /objects/obs1/rear/gps/fix => 12
+  /objects/obs1/rear/gps/rtkfix => 69
+  /objects/obs1/rear/gps/time => 50
+  /radar/points => 136
+  /radar/range => 136
+  /radar/tracks => 136
+  /vehicle/brake_info_report => 342
+  /vehicle/brake_report => 341
+  /vehicle/filtered_accel => 341
+  /vehicle/fuel_level_report => 68
+  /vehicle/gear_report => 137
+  /vehicle/gps/fix => 7
+  /vehicle/gps/time => 7
+  /vehicle/gps/vel => 7
+  /vehicle/imu/data_raw => 682
+  /vehicle/joint_states => 1025
+  /vehicle/misc_1_report => 137
+  /vehicle/sonar_cloud => 34
+  /vehicle/steering_report => 341
+  /vehicle/surround_report => 34
+  /vehicle/suspension_report => 342
+  /vehicle/throttle_info_report => 684
+  /vehicle/throttle_report => 341
+  /vehicle/tire_pressure_report => 14
+  /vehicle/twist => 341
+  /vehicle/wheel_speed_report => 684
+  /velodyne_nodelet_manager/bond => 28
+  /velodyne_packets => 68
+Total: 11984
+
+[ 8_f.bag ]
+  /can_bus_dbw/can_rx => 2928
+  /diagnostics => 43
+  /diagnostics_agg => 12
+  /diagnostics_toplevel_state => 12
+  /image_raw => 99
+  /objects/capture_vehicle/front/gps/fix => 37
+  /objects/capture_vehicle/front/gps/rtkfix => 42
+  /objects/capture_vehicle/front/gps/time => 39
+  /objects/capture_vehicle/rear/gps/fix => 6
+  /objects/capture_vehicle/rear/gps/rtkfix => 42
+  /objects/capture_vehicle/rear/gps/time => 33
+  /objects/obs1/rear/gps/fix => 7
+  /objects/obs1/rear/gps/rtkfix => 42
+  /objects/obs1/rear/gps/time => 28
+  /radar/points => 82
+  /radar/range => 82
+  /radar/tracks => 82
+  /vehicle/brake_info_report => 206
+  /vehicle/brake_report => 206
+  /vehicle/filtered_accel => 206
+  /vehicle/fuel_level_report => 41
+  /vehicle/gear_report => 82
+  /vehicle/gps/fix => 5
+  /vehicle/gps/time => 5
+  /vehicle/gps/vel => 5
+  /vehicle/imu/data_raw => 412
+  /vehicle/joint_states => 619
+  /vehicle/misc_1_report => 82
+  /vehicle/sonar_cloud => 20
+  /vehicle/steering_report => 206
+  /vehicle/surround_report => 20
+  /vehicle/suspension_report => 207
+  /vehicle/throttle_info_report => 412
+  /vehicle/throttle_report => 205
+  /vehicle/tire_pressure_report => 8
+  /vehicle/twist => 206
+  /vehicle/wheel_speed_report => 413
+  /velodyne_nodelet_manager/bond => 16
+  /velodyne_packets => 41
+Total: 7239
+
+lenovo@lenovo-Default-string:~/didi/DiDi-Udacity-Data-Reader$