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Are serious things done with ROS in Python?


#1

I am wondering whether ROS programming for serious projects always ends up being in C++. In other words, is Python the “onramp” to lower the barriers, but everyone graduates to C++?


#2

Our organization certainly has production Python code in use in our client sites. There’s always a matter of the right tool for the job, though - we don’t have any controls or perception code written in Python, that’s all in C++.


#3

There are definitely serious things done in Python. In fact, a large amount of the every day tools we use are python-based. I think that performance reasons lead to the C++ favoritism, honestly.


#4

Some other “serious” things done in Python:


#5

There are also drivers done on Python (specially ones that deal with Serial devices):

And hey, lots of deep learning happening in Python (and then wrapped in ROS).


#6

Everyone loves a good statistic, so I’ve put together a small python script that collects the major language used in each released ROS repository, as classified by GitHub. You can clearly see that C++ is the dominant language, but Python is also used a lot, including for “serious stuff”.

Some caveats in the statistics:

  • The list only shows the major language used in a repo (winner takes it all). Often, ROS repos contain both C++ and Python (or other) code, but C++ wins by LOC, so smaller languages are underrepresented in the list below.
  • I’m only counting repos, but the repos differ in size a lot. Some contain many packages with several 10,000 LOC, some are single-package repos with only a couple dozen LOC.

To answer the question, I wouldn’t say people “graduate” from Python to C++. Personally, I use both, depending on the task. My main criterion isn’t performance, but library support (although the two are linked). If you’re processing a lot of point clouds, you’re probably going to use things like PCL and Octomap, which means C++. For image processing, you’re probably going to use OpenCV, which has bindings both for C++ and Python. Most high-level executive frameworks (such as executive_smach or one of the behavior tree frameworks) are written in Python. And for small helper nodes, one-off scripts, or anything involving web sockets or REST APIs, I also prefer Python.

Here are the results:

Main languages in ROS repos by popularity

rank Language repos percent
1. C++ 350 55.0%
2. Python 158 24.8%
3. CMake 82 12.9%
4. C 15 2.4%
5. Common Lisp 8 1.3%
6. None 7 1.1%
7. Java 4 0.6%
8. EmberScript 3 0.5%
9. Shell 2 0.3%
10. HTML 2 0.3%
11. Arduino 1 0.2%
12. Emacs Lisp 1 0.2%
13. Lua 1 0.2%
14. Protocol Buffer 1 0.2%
15. C# 1 0.2%

Top 100 ROS repos by GitHub stars

rank repo name stars language
1. IntelRealSense/librealsense 1291 C++
2. ros/ros 697 Python
3. wjwwood/serial 520 C++
4. introlab/rtabmap 489 C++
5. OctoMap/octomap 382 C++
6. ros-planning/navigation 317 C++
7. ethz-asl/grid_map 281 C++
8. AutonomyLab/ardrone_autonomy 264 C
9. ros/ros_comm 239 Python
10. dartsim/dart 213 C++
11. introlab/find-object 210 C++
12. vrpn/vrpn 200 C
13. intel-ros/realsense 193 C++
14. robopeak/rplidar_ros 191 C++
15. ros-planning/moveit 173 C++
16. ros-visualization/rviz 170 C++
17. mavlink/mavros 169 C++
18. introlab/rtabmap_ros 162 C++
19. ros-drivers/rosserial 162 C++
20. cra-ros-pkg/robot_localization 160 C++
21. ros/ros_tutorials 144 C++
22. RobotWebTools/rosbridge_suite 139 Python
23. leggedrobotics/darknet_ros 132 C++
24. ros/catkin 129 Python
25. ros-drivers/velodyne 128 C++
26. ros-perception/slam_gmapping 127 C++
27. ccny-ros-pkg/imu_tools 125 C++
28. ros-industrial/universal_robot 125 Python
29. orocos/orocos_kinematics_dynamics 122 C++
30. ros-simulation/gazebo_ros_pkgs 119 C++
31. ros-controls/ros_control 111 C++
32. rosjava/rosjava_core 108 Java
33. ros-perception/image_pipeline 108 C++
34. turtlebot/turtlebot 102 C++
35. facontidavide/PlotJuggler 102 C++
36. ROBOTIS-GIT/turtlebot3 100 Python
37. ROBOTIS-GIT/DynamixelSDK 93 C#
38. rst-tu-dortmund/teb_local_planner 90 C++
39. ros-perception/vision_opencv 84 C++
40. turtlebot/turtlebot_apps 78 C++
41. yujinrobot/kobuki 75 C++
42. ros-controls/ros_controllers 72 C++
43. ankitdhall/lidar_camera_calibration 71 C++
44. ipa320/cob_driver 68 C++
45. PickNikRobotics/rviz_visual_tools 67 C++
46. swri-robotics/mapviz 66 C++
47. ros-drivers/usb_cam 65 C++
48. plasmodic/ecto 64 C++
49. AutonomyLab/bebop_autonomy 63 C++
50. wg-perception/people 61 C++
51. ros/geometry 59 C++
52. ipa320/cob_common 59 Python
53. AndreaCensi/csm 57 C
54. ros-perception/perception_pcl 57 C++
55. ipa320/cob_simulation 57 Python
56. Intermodalics/tango_ros 56 C++
57. clearpathrobotics/robot_upstart 53 Python
58. jsk-ros-pkg/jsk_recognition 52 C++
59. ipa320/cob_extern 52 C
60. intel/ros_intel_movidius_ncs 50 C++
61. lagadic/vision_visp 49 C++
62. AutonomyLab/create_autonomy 49 C++
63. RobotWebTools/web_video_server 48 C++
64. fkie/multimaster_fkie 46 Python
65. skasperski/navigation_2d 45 C++
66. ccny-ros-pkg/scan_tools 44 C++
67. stdr-simulator-ros-pkg/stdr_simulator 44 C++
68. ros-industrial/industrial_core 43 C++
69. ros-planning/navigation_tutorials 43 C++
70. ipa320/cob_robots 43 Python
71. ros-drivers/pointgrey_camera_driver 43 C++
72. orocos-toolchain/log4cpp 42 C++
73. ros-perception/openslam_gmapping 42 C++
74. yujinrobot/yujin_ocs 41 C++
75. ros-industrial/ros_canopen 41 C++
76. ros-industrial/abb 40 C++
77. paulbovbel/frontier_exploration 40 C++
78. ros/geometry2 38 C++
79. ros/executive_smach 38 Python
80. ros-industrial/kuka_experimental 37 C++
81. ipa320/schunk_modular_robotics 36 C++
82. OctoMap/octomap_mapping 36 C++
83. arebgun/dynamixel_motor 35 Python
84. youbot/youbot_driver 35 C++
85. beltransen/velo2cam_calibration 34 C++
86. ros/common_msgs 34 C++
87. davetcoleman/ros_control_boilerplate 34 C++
88. hasauino/rrt_exploration 33 C++
89. ros/actionlib 33 C++
90. ros-visualization/visualization_tutorials 32 C++
91. ros-drivers/joystick_drivers 32 Python
92. magazino/move_base_flex 32 C++
93. turtlebot/turtlebot_simulator 32 EmberScript
94. cbandera/rosparam_handler 31 Python
95. ros-naoqi/nao_robot 30 Python
96. ipa320/cob_command_tools 30 Python
97. mrpt-ros-pkg/mrpt_navigation 30 C++
98. ethz-asl/rqt_multiplot_plugin 30 C++
99. wg-perception/object_recognition_core 30 C++
100. orocos/rtt_ros_integration 30 C++

#7

After the 2013 NASA Sample Return Robot Centennial Challenge I asked the teams about the software used. The results are on my blog:

The primary language was C++ whether the team used ROS or not. That was 7 of the 10 teams that provided information. Some python was used in conjunction with C++. One team that used a combination regretted, without further explanation, the python code in their system. (Please, no language war on that point. Just reporting…)

The results were similar for the 2014 challenge but I didn’t formally record the results.


#8

I find this topic pretty interesting and starting from @Martin_Guenther work, I digged a bit more in.

I made another script (warning, I mostly executed everything on an ipython terminal by parts, so I may have missed something) to clone the repos (in github, I tried to clone also the ones in bitbucket but it fails on my machine for some unrelated reason) and to compute the LOC on them for C++ and Python.

The output is:

From 625 packages analysed
There are 413 packages using C++
There are 317 packages using Python
And, actually, using both languages: 193
88.8747413208 % is CPP code
11.1252586792 % is Python code

I also recreated the table with this LOC data:

rank repo name stars language
1. IntelRealSense/librealsense 1295 C++ (99.6), Python (0.4)
2. ros/ros 697 Python (95.6), C++ (4.4)
3. wjwwood/serial 521 C++ (99.7), Python (0.3)
4. introlab/rtabmap 490 C++ (100.0), Python (0.0)
5. OctoMap/octomap 383 C++ (99.7), Python (0.3)
6. ros-planning/navigation 320 C++ (99.1), Python (0.9)
7. ethz-asl/grid_map 281 C++ (99.7), Python (0.3)
8. AutonomyLab/ardrone_autonomy 264 C
9. ros/ros_comm 239 Python (44.8), C++ (55.2)
10. dartsim/dart 214 C++ (98.7), Python (1.3)
11. introlab/find-object 210 C++ (100.0), Python (0.0)
12. vrpn/vrpn 201 C
13. intel-ros/realsense 194 C++ (99.2), Python (0.8)
14. robopeak/rplidar_ros 191 C++ (100.0), Python (0.0)
15. ros-planning/moveit 173 C++
16. ros-visualization/rviz 171 C++ (97.6), Python (2.4)
17. mavlink/mavros 169 C++ (92.1), Python (7.9)
18. ros-drivers/rosserial 164 C++ (67.2), Python (32.8)
19. introlab/rtabmap_ros 162 C++ (99.4), Python (0.6)
20. cra-ros-pkg/robot_localization 161 C++ (99.4), Python (0.6)
21. ros/ros_tutorials 144 C++
22. RobotWebTools/rosbridge_suite 139 Python (100.0), C++ (0.0)
23. leggedrobotics/darknet_ros 133 C++ (100.0), Python (0.0)
24. ros/catkin 130 Python (97.6), C++ (2.4)
25. ros-perception/slam_gmapping 128 C++ (94.3), Python (5.7)
26. ros-drivers/velodyne 128 C++ (95.2), Python (4.8)
27. ros-industrial/universal_robot 127 Python (54.9), C++ (45.1)
28. ccny-ros-pkg/imu_tools 125 C++ (100.0), Python (0.0)
29. orocos/orocos_kinematics_dynamics 122 C++ (97.4), Python (2.6)
30. ros-simulation/gazebo_ros_pkgs 120 C++ (96.3), Python (3.7)
31. ros-controls/ros_control 112 C++ (92.0), Python (8.0)
32. rosjava/rosjava_core 110 Java
33. ros-perception/image_pipeline 109 C++ (77.9), Python (22.1)
34. turtlebot/turtlebot 103 C++ (88.9), Python (11.1)
35. facontidavide/PlotJuggler 103 C++ (100.0), Python (0.0)
36. ROBOTIS-GIT/turtlebot3 101 Python (65.0), C++ (35.0)
37. ROBOTIS-GIT/DynamixelSDK 94 C#
38. rst-tu-dortmund/teb_local_planner 90 C++ (95.4), Python (4.6)
39. ros-perception/vision_opencv 85 C++ (84.7), Python (15.3)
40. turtlebot/turtlebot_apps 79 C++ (65.2), Python (34.8)
41. yujinrobot/kobuki 76 C++ (55.0), Python (45.0)
42. ros-controls/ros_controllers 73 C++ (96.3), Python (3.7)
43. ankitdhall/lidar_camera_calibration 72 C++ (100.0), Python (0.0)
44. PickNikRobotics/rviz_visual_tools 69 C++ (100.0), Python (0.0)
45. ipa320/cob_driver 68 C++ (94.2), Python (5.8)
46. swri-robotics/mapviz 66 C++ (100.0), Python (0.0)
47. plasmodic/ecto 65 C++ (71.6), Python (28.4)
48. ros-drivers/usb_cam 65 C++ (100.0), Python (0.0)
49. AutonomyLab/bebop_autonomy 63 C++ (94.9), Python (5.1)
50. wg-perception/people 61 C++ (97.0), Python (3.0)
51. ros/geometry 59 C++ (82.7), Python (17.3)
52. ipa320/cob_common 59 Python (100.0), C++ (0.0)
53. ros-perception/perception_pcl 58 C++ (99.6), Python (0.4)
54. AndreaCensi/csm 57 C
55. ipa320/cob_simulation 57 Python (100.0), C++ (0.0)
56. Intermodalics/tango_ros 57 C++ (100.0), Python (0.0)
57. clearpathrobotics/robot_upstart 54 Python (100.0), C++ (0.0)
58. jsk-ros-pkg/jsk_recognition 52 C++ (85.3), Python (14.7)
59. ipa320/cob_extern 52 C
60. intel/ros_intel_movidius_ncs 50 C++ (100.0), Python (0.0)
61. AutonomyLab/create_autonomy 50 C++ (100.0), Python (0.0)
62. lagadic/vision_visp 49 C++ (99.2), Python (0.8)
63. RobotWebTools/web_video_server 48 C++ (100.0), Python (0.0)
64. skasperski/navigation_2d 46 C++ (100.0), Python (0.0)
65. fkie/multimaster_fkie 46 Python (100.0), C++ (0.0)
66. ccny-ros-pkg/scan_tools 44 C++ (100.0), Python (0.0)
67. stdr-simulator-ros-pkg/stdr_simulator 44 C++ (98.6), Python (1.4)
68. ros-industrial/industrial_core 43 C++ (100.0), Python (0.0)
69. ros-planning/navigation_tutorials 43 C++ (100.0), Python (0.0)
70. ipa320/cob_robots 43 Python (100.0), C++ (0.0)
71. ros-drivers/pointgrey_camera_driver 43 C++
72. orocos-toolchain/log4cpp 42 C++ (100.0), Python (0.0)
73. ros-perception/openslam_gmapping 42 C++ (100.0), Python (0.0)
74. yujinrobot/yujin_ocs 41 C++ (83.3), Python (16.7)
75. paulbovbel/frontier_exploration 41 C++ (100.0), Python (0.0)
76. ros-industrial/ros_canopen 41 C++ (100.0), Python (0.0)
77. ros-industrial/abb 40 C++ (100.0), Python (0.0)
78. ros/geometry2 39 C++ (91.9), Python (8.1)
79. ros/executive_smach 39 Python (100.0), C++ (0.0)
80. OctoMap/octomap_mapping 37 C++ (99.0), Python (1.0)
81. ros-industrial/kuka_experimental 37 C++ (100.0), Python (0.0)
82. ipa320/schunk_modular_robotics 36 C++ (99.3), Python (0.7)
83. arebgun/dynamixel_motor 35 Python (100.0), C++ (0.0)
84. youbot/youbot_driver 35 C++ (100.0), Python (0.0)
85. davetcoleman/ros_control_boilerplate 35 C++
86. ros/actionlib 34 C++ (68.3), Python (31.7)
87. beltransen/velo2cam_calibration 34 C++ (100.0), Python (0.0)
88. ros/common_msgs 34 C++ (82.5), Python (17.5)
89. hasauino/rrt_exploration 33 C++ (49.8), Python (50.2)
90. magazino/move_base_flex 33 C++ (97.0), Python (3.0)
91. turtlebot/turtlebot_simulator 33 EmberScript
92. vanadiumlabs/arbotix_ros 32 Python (93.1), C++ (6.9)
93. ros-visualization/visualization_tutorials 32 C++ (74.8), Python (25.2)
94. ros-drivers/joystick_drivers 32 Python (68.8), C++ (31.2)
95. cbandera/rosparam_handler 31 Python (54.3), C++ (45.7)
96. wg-perception/object_recognition_core 31 C++ (54.3), Python (45.7)
97. ros-naoqi/nao_robot 30 Python (95.1), C++ (4.9)
98. ipa320/cob_command_tools 30 Python (79.5), C++ (20.5)
99. mrpt-ros-pkg/mrpt_navigation 30 C++ (100.0), Python (0.0)
100. ethz-asl/rqt_multiplot_plugin 30 C++ (99.9), Python (0.1)

I think Python has it’s position on glueing things together, dealing with text, making apps and tools, and overall taking advantage of the big amount of third party libraries that ease doing stuff. If you need speed, C++ for sure. If you need something done quick, Python I’d say.


#9

Nice work, @awesomebytes! :slight_smile:


#10

I’ve digged a bit more, I was curious on what is Python doing in packages that have both Python and C++? (Updated the gist).

You can find a list of the Python filenames for every package that contains C++ & Python here: https://pastebin.com/aiY5c1t2

My conclusion by looking at it, just with the filenames and the folder hierarchy (193 is too many packages to check them all 1 by 1, sorry!) with some grepping and some manual reading:

  • People make tools using Python (commandline tools, filtering tools, debugging tools).
  • People make tests* using Python (1059 files with test in the name/folderpath).
  • People script things (duh) using Python (robot motions, if this then that, migration scripts, calibrations).
  • People make demos using Python (28 files using the word demo).
  • People make graphical stuff with Python (344 files/paths with rqt).
  • People make fake stuff with Python (14 files with the word fake, as in fake_publisher, probably for testing/tutorial purposes).
  • People provide examples in Python (93 files with the word example).

*Haven’t checked if just in Python, or some kind of specific type of test is rather done in Python than C++, I personally do functional tests that way, as in, checking the topics/services/action servers do what they should, and I get the feeling it’s the same by the filenames I’ve glanced over (many ‘send’ ‘publish’ ‘pub’ ‘sub’ ).

I hope someone else finds it interesting!