[ROS Q&A] 033 - New message is different from previous message in a subscribed rostopic?

More ROS Learning Resources: https://goo.gl/DuTPtK

Hi all,
when working with ROS, on almost 99% of the cases we use ROS Topics.

There are some scenarios where we only can "do something" when a message published on a topic is different from a previous message.

In this video we show how to solve this by answering a real question.

The real question that we answer can be found on the following link:

https://answers.ros.org/question/270696/how-to-know-if-new-message-is-different-from-previous-message-in-a-subscribed-rostopic/

---------- Want to learn ROS really FAST and master the latest Robotics topics? ----------
:: Visit Robot Ignite Academy, the online Academy that teaches you ROS really FAST, from beginner to master, using only a web browser: https://goo.gl/LBT7EN
Robot Ignite Academy is an integrated ROS learning platform which contains a series of online ROS tutorials tied to online simulations, giving you the tools and knowledge to understand and create any ROS based robotics development.

---------- Are you a ROS expert and want to develop FAST your next ROS project? ----------

:: Then, use the ROS Development Studio (RDS) for your next project: https://goo.gl/EtFqmE
With the ROS Development Studio, you will be able to:
- Develop ROS programs for robots in a faster way, with an already setup IDE environment that includes autocomplete.
- Test the programs in real time on the provided simulated robots. Use the provided simulations or upload your own. Quickly see the results of your programming.
- Debug using graphical ROS tools.
- Test what you have developed on RDS in the real robot (if you have it :wink:
all of these are using ONLY a web browser without any installation and not limited by any operating system. DEVELOP FOR ROS USING WINDOWS, LINUX OR OSX.