ros_packages Ros python包新手教程，中文见后

It is a tutorial for build ros packages.

ros_python_template

build python packages. In ROS we also use Distutils to create a package(It is ok if you are not familier with that),but there are slightly differences. We don't install the package in the OS but under catkin, but still we use setup.py

Example for the package:
1.create package.
mkdir src
under src
catkin_create_pkg python_package std_msgs rospy roscpp sensor_msgs cv_bridge message_filters
2.Uncomment the following lines in the cmakelist under package root.
catkin_python_setup
this makes camke execute setup.py, and different from run it directly,but install everything in catkin_ws for more ditals see http://docs.ros.org/api/catkin/html/user_guide/setup_dot_py.html
3.Uncomment the following lines in the cmakelist under package root.
install(PROGRAMS
scripts/my_python_script
DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
)
to install the executables for details see: http://docs.ros.org/melodic/api/catkin/html/howto/format2/installing_python.html

4.create setup.py under the package.
how to create it, depends on the structure of your package https://docs.python.org/2/distutils/examples.html
https://docs.python.org/2/distutils/setupscript.html
e.g import python_imapro_package.imapro
if name == 'main':
python_imapro_package.imapro.imagetovedio()

应邀搞个新手ros教程（完全新手请先看ros官网的docu）也想自己留存一些模板，希望大家提宝贵意见以及纠错&对程序改进

从零创建新python包 ：

ros环境下编译python的说明：
ros下面我们其实也是使用了Distutils来做python包的（不熟悉这个也无所谓，可以google下Distutils有个概念），不过有些区别
我们并不把安装的对象安装到系统里，而是安装在catkin下，但是依然使用setup.py

下面举例具体说明
1.创建package
mkdir src
并在src下面
catkin_create_pkg python_package std_msgs rospy roscpp sensor_msgs cv_bridge message_filters
2.取消packge根目录下，cmakelist里catkin_python_setup的注释
这里使得cmake执行setup.py的安装，并且不同于直接运行，而是安装在catkin里恰当的位置
说明如下
http://docs.ros.org/api/catkin/html/user_guide/setup_dot_py.html
3.取消packge根目录下，cmakelist里
install(PROGRAMS
scripts/my_python_script
DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
)
的注释来安装可执行文件
说明见下
http://docs.ros.org/melodic/api/catkin/html/howto/format2/installing_python.html
ros的可执行文件，不是在整体的catkin下面，这样避免冲突。
标准的ros规范是把可执行的（rosrun的东西）放在/node或者/script下面，不带.py的后缀,避免在rosrun的时候打后缀。

4.现在我们来创建一个python包(不是ros包，或者说从属于ros包的python包)
需要一个setup.py放在和cmakelist同样的文件夹下，其余的和普通的python包区别不大。
这里简单介绍下
如何编写setup.py其实取决于你想往哪放这个包（或者不要包就是几个py文件） 说明和举例见
https://docs.python.org/2/distutils/examples.html
https://docs.python.org/2/distutils/setupscript.html

重点1：
package_dir={'': 'src'}指的是把root放在src这个文件夹下。这要找modules和package会在src这个文件夹下找
packages=['python_Imapro_package'] 则是说我这个包叫python_Imapro_package，你需要干的事情就是在root（这里是src）下建立一个文件夹叫python_Imapro_package。里面是包的内容

重点2：
python_imapro_package 下面要放一个空的叫__init__.py的东西，这个是说，大家好我是包。
然后在 python_imapro_package 下面放你写的东西就好了
可以在cmakelist目录下再建一个node文件夹，里面放可执行的.py文件，在这个文件里调用src下面的包。

如：
import python_imapro_package.imapro
if name == 'main':
python_imapro_package.imapro.imagetovedio()

ros_package_cpp

第一步创建包 mkdir catkin_ws
cd catkin_ws
mkdir src
cd src
catkin_create_pkg cpp_package std_msgs rospy roscpp sensor_msgs cv_bridge message_filters

第二步修改cmakelist

An example for cmakelist

ros的cmakelist和普通的区别不大，这里再简单说明下 cmake_minimum_required(VERSION 2.8.3)

project(nodename)

1. 找到需要的依赖 find_package(catkin REQUIRED COMPONENTS cv_bridge message_filters roscpp rospy sensor_msgs std_msgs pcl_ros tf2_ros ) find_package(OpenCV REQUIRED) //opencv必须单独写

2. System dependencies are found with CMake's conventions find_package(Boost REQUIRED COMPONENTS system) //boost 必须单独写

3. 产生这个包的信息，使得其他包和后面的函数能用这个包的信息 catkin_package( INCLUDE_DIRS include LIBRARIES cpp_package CATKIN_DEPENDS cv_bridge message_filters roscpp rospy sensor_msgs std_msgs DEPENDS system_lib )

4 告诉编译器我的include位置，放你的.hpp文件 同时include的时候，不用给出相对路径位置了，会直接搜索include文件夹 Specify additional locations of header files Your package locations should be listed before other locations include_directories( include ${catkin_INCLUDE_DIRS} ${OpenCV_INCLUDE_DIRS} ${PCL_INCLUDE_DIRS} )

5 声明引用的其他cpp，一般是hpp中函数的实现 Declare a C++ library add_library(${PROJECT_NAME} src/${PROJECT_NAME}/cpp_functions.cpp )

6 声明其他依赖 Add cmake target dependencies of the executable same as for the library above add_dependencies(${PROJECT_NAME}_node ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})

7 把上面的lib链接到execu Specify libraries to link a library or executable target against target_link_libraries(${PROJECT_NAME}_node ${catkin_LIBRARIES} )

举例 add_executable(foo src/foo.cpp) add_library(moo src/moo.cpp) target_link_libraries(foo moo) -- This links foo against libmoo.so