Nepu-Gear

Derivative example:

Example of compiling and running:

 cd ~/catkin_ws  
 catkin_make  
 source devel/setup.bash  
 rosrun [package_name] [program_name]  

In the examples the workspace folder is called "catkin_ws"

It will be updated with more examples ...

Only write the following commands in the Terminal:

1.- Workspace:

Create and build and empty workspace:

For the examples the workspace is called “catkin_ws”:

Create a package:

Go to the source directory of the workspace:

 cd ~/catkin_ws/src  

then create a package

 catkin_create_pkg [depend1] [depend2] [depend3]  

catkin_create_pkg requires that you give it a package_name and optionally a list of dependencies on which that package depends.

Example:

 catkin_create_pkg turtlebot_controller turtlesim geometry_msgs std_msgs roscpp rospy  

The name of the package is "turtlebot_controller" and the dependences are "turtlesim", "geometry_msgs", "std_msgs", "roscpp" and "rospy"

Build the packages in the catkin workspace: 

Go to main workspace directory: 

 cd ~/catkin_ws   

then build the packages: 

 catkin_make   

To add the workspace to the ROS environment : 

 . ~/catkin_ws/devel/setup.bash  

2.- Running and see states:

Start using ROS:

 roscore  

this command is the first thing you should run when using ROS.

Run a node of a package:

 rosrun [package_name] [node_name]  

Displays ROS nodes that are currently running:

 rosnode list  

/rosout is always present

Display more information about a node currently running:

 rosnode info [node]  

Example:

 rosnode info /rosout  

Displays ROS topics that are currently present:

 rostopic list  

See the actual messages that are being published on a topic:

 rostopic echo [topic]  

Get information about ROS topics:

 rostopic type [topic]  

It will be updated with more commands ...

Python examples: 

With arange (use the form start,end,step):

arange documentation:
http://docs.scipy.org/doc/numpy/reference/generated/numpy.arange.html#numpy.arange

With linespace

linespace documentation:
http://docs.scipy.org/doc/numpy/reference/generated/numpy.linspace.html

Matlab examples:

Creating a vector of values (form start:step:end)

With linespace

1.- Install the prerequisite software:

 sudo xcode-select --install  

 sudo xcode-select -p  

In my case this command print:

 /Applications/Xcode.app/Contents/Developer  

1.5 Then, run the next command:

 sudo xcode-select -switch <xcode path>  

Where in my case is:

 sudo xcode-select -switch /Applications/Xcode.app/Contents/Developer  

1.6.-  Go to the terminal and update the package index with:

 sudo port -v selfupdate  

and

 sudo port upgrade outdated   

2.- Install Python and basic packages:

2.1 Install  Python  with:

 sudo port install python27  

2.2 Select the version of python as:

 sudo port select --set python python27  

2.3 Install the basic packages of scientific computing (matplotlib and numpy are required for use OpenCV).

 sudo port install py27-numpy py27-matplotlib py27-scipy  

3.- Install OpenCV

3.1 Install OpenCV with support for Python with:

 sudo port install opencv +python27  

3.2 To verify that the installation is correct, write in the terminal:

 python  

The, in the python terminal and write:

 import cv2  

If no error is shown then the installation was successful.

Note: I'm sorry for my poor grammar!

Para ello se debe escribir en la terminal de python:

 import os  

Si se desea conocer el directorio actual de trabajo escribir:

 os.getcwd()  

Para cambiar de directorio simplemente hay que usar la función os.chdir y especificar la ruta del nuevo directorio, por ejemplo en el escritorio en Windows:

 os.chdir('C:\\Users\\username\\Desktop')  

Donde username es el nombre de usuario.

Para agregar código con un formato agradable y numerado como:



Simplemente hay que entrar en el modo texto y agregar:
Donde se puede se puede sustituir "python" otro lenguaje de programación soportado. Un ejemplo se muestra en  la siguiente imagen.



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