Remove Tf2 time tutorials for Python (#4384) (#4386)

* Small update for language in tf2 static transforms.

* Small language fixups in tf2 broadcaster tutorials.

* Small language updates in Writing a tf2 listener.

* Small clarification in Add-a-frame tutorials.

* Small updates to the Learning-about-tf2-and-time-cpp tutorial.

* Remove the python tf2 tutorials.

They have not worked for a very long time, and in point of
fact with the current tf2_py code, they cannot work.
Remove them until the time we actually fix the tf2_py
code, at which point we can reintroduce them.

Signed-off-by: Chris Lalancette <[email protected]>
(cherry picked from commit cb0e0be)

Co-authored-by: Chris Lalancette <[email protected]>

source/Concepts/Intermediate/About-Tf2.rst

@@ -56,8 +56,8 @@ If you want to define static transforms in your tf2 tree, take a look at the "Wr
 You can also learn how to add fixed and dynamic frames to your tf2 tree in the "Adding a frame" :doc:`(Python) <../../Tutorials/Intermediate/Tf2/Adding-A-Frame-Py>` :doc:`(C++) <../../Tutorials/Intermediate/Tf2/Adding-A-Frame-Cpp>` tutorial.
 
 Once you are finished with the basic tutorials, you can move on to learn about tf2 and time.
-The tf2 and time tutorial :doc:`(Python) <../../Tutorials/Intermediate/Tf2/Learning-About-Tf2-And-Time-Py>` :doc:`(C++) <../../Tutorials/Intermediate/Tf2/Learning-About-Tf2-And-Time-Cpp>` teaches the basic principles of tf2 and time.
-The advanced tutorial about tf2 and time :doc:`(Python) <../../Tutorials/Intermediate/Tf2/Time-Travel-With-Tf2-Py>` :doc:`(C++) <../../Tutorials/Intermediate/Tf2/Time-Travel-With-Tf2-Cpp>` teaches the principles of time traveling with tf2.
+The tf2 and time tutorial :doc:`(C++) <../../Tutorials/Intermediate/Tf2/Learning-About-Tf2-And-Time-Cpp>` teaches the basic principles of tf2 and time.
+The advanced tutorial about tf2 and time :doc:`(C++) <../../Tutorials/Intermediate/Tf2/Time-Travel-With-Tf2-Cpp>` teaches the principles of time traveling with tf2.
 
 Paper
 -----

source/Tutorials/Intermediate/Tf2/Adding-A-Frame-Cpp.rst

@@ -182,7 +182,7 @@ Finally, add the ``install(TARGETS…)`` section so ``ros2 run`` can find your e
 ~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Now let's create a launch file for this example.
-With your text editor, create a new file called ``launch/turtle_tf2_fixed_frame_demo_launch.py``, and add the following lines:
+With your text editor, create a new file called ``turtle_tf2_fixed_frame_demo_launch.py`` in the ``src/learning_tf2_cpp/launch`` directory, and add the following lines:
 
 .. code-block:: python
 
@@ -469,7 +469,7 @@ Finally, add the ``install(TARGETS…)`` section so ``ros2 run`` can find your e
 2.3 Write the launch file
 ~~~~~~~~~~~~~~~~~~~~~~~~~
 
-To test this code, create a new launch file ``launch/turtle_tf2_dynamic_frame_demo_launch.py`` and paste the following code:
+To test this code, create a new launch file ``turtle_tf2_dynamic_frame_demo_launch.py`` in the ``src/learning_tf2_cpp/launch`` directory and paste the following code:
 
 .. code-block:: python
 

source/Tutorials/Intermediate/Tf2/Adding-A-Frame-Py.rst

@@ -160,7 +160,7 @@ Add the following line between the ``'console_scripts':`` brackets:
 ~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Now let's create a launch file for this example.
-With your text editor, create a new file called ``launch/turtle_tf2_fixed_frame_demo_launch.py``, and add the following lines:
+With your text editor, create a new file called ``turtle_tf2_fixed_frame_demo_launch.py`` in the ``src/learning_tf2_py/launch`` directory, and add the following lines:
 
 .. code-block:: python
 
@@ -204,7 +204,6 @@ The last part of the code will add our fixed ``carrot1`` frame to the turtlesim
         name='fixed_broadcaster',
     ),
 
-
 1.4 Build
 ~~~~~~~~~
 
@@ -427,7 +426,7 @@ Add the following line between the ``'console_scripts':`` brackets:
 2.3 Write the launch file
 ~~~~~~~~~~~~~~~~~~~~~~~~~
 
-To test this code, create a new launch file ``launch/turtle_tf2_dynamic_frame_demo_launch.py`` and paste the following code:
+To test this code, create a new launch file ``turtle_tf2_dynamic_frame_demo_launch.py`` in the ``src/learning_tf2_py/launch`` directory and paste the following code:
 
 .. code-block:: python
 

source/Tutorials/Intermediate/Tf2/Learning-About-Tf2-And-Time-Cpp.rst

@@ -21,19 +21,19 @@ Background
 ----------
 
 In previous tutorials, we recreated the turtle demo by writing a :doc:`tf2 broadcaster <Writing-A-Tf2-Broadcaster-Cpp>` and a :doc:`tf2 listener <Writing-A-Tf2-Listener-Cpp>`.
-We also learned how to :doc:`add a new frame to the transformation tree <./Adding-A-Frame-Cpp>` and learned how tf2 keeps track of a tree of coordinate frames.
+We also learned how to :doc:`add a new frame to the transformation tree <Adding-A-Frame-Cpp>` and learned how tf2 keeps track of a tree of coordinate frames.
 This tree changes over time, and tf2 stores a time snapshot for every transform (for up to 10 seconds by default).
 Until now we used the ``lookupTransform()`` function to get access to the latest available transforms in that tf2 tree, without knowing at what time that transform was recorded.
 This tutorial will teach you how to get a transform at a specific time.
 
 Tasks
 -----
 
-1 tf2 and time
-^^^^^^^^^^^^^^
+1 Update the listener node
+^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-So let's go back to where we ended in the :doc:`adding a frame tutorial <./Adding-A-Frame-Cpp>`.
-Go to ``learning_tf2_cpp`` package.
+Let's go back to where we ended in the :doc:`adding a frame tutorial <Adding-A-Frame-Cpp>`.
+Go to the ``learning_tf2_cpp`` package.
 Open ``turtle_tf2_listener.cpp`` and take a look at the ``lookupTransform()`` call:
 
 .. code-block:: C++
@@ -76,7 +76,7 @@ You will notice that it fails and outputs something similar to this:
 
 .. code-block:: console
 
-   [INFO] [1629873136.345688064] [listener]: Could not transform turtle1 to turtle2: Lookup would
+   [INFO] [1629873136.345688064] [listener]: Could not transform turtle2 to turtle1: Lookup would
    require extrapolation into the future.  Requested time 1629873136.345539 but the latest data
    is at time 1629873136.338804, when looking up transform from frame [turtle1] to frame [turtle2]
 
@@ -87,8 +87,8 @@ Firstly, each listener has a buffer where it stores all the coordinate transform
 Secondly, when a broadcaster sends out a transform, it takes some time before that transform gets into the buffer (usually a couple of milliseconds).
 As a result, when you request a frame transform at time "now", you should wait a few milliseconds for that information to arrive.
 
-2 Wait for transforms
-^^^^^^^^^^^^^^^^^^^^^
+2 Fix the listener node
+^^^^^^^^^^^^^^^^^^^^^^^
 
 tf2 provides a nice tool that will wait until a transform becomes available.
 You use this by adding a timeout parameter to ``lookupTransform()``.
@@ -108,8 +108,8 @@ To fix this, edit your code as shown below (add the last timeout parameter):
 The ``lookupTransform()`` can take four arguments, where the last one is an optional timeout.
 It will block for up to that duration waiting for it to timeout.
 
-3 Checking the results
-^^^^^^^^^^^^^^^^^^^^^^
+3 Check the results
+^^^^^^^^^^^^^^^^^^^
 
 You can now build the package and run the launch file.
 

source/Tutorials/Intermediate/Tf2/Tf2-Main.rst

@@ -27,9 +27,7 @@ If you want to learn both C++ and Python, you should go through the tutorials on
    Writing-A-Tf2-Listener-Cpp
    Adding-A-Frame-Py
    Adding-A-Frame-Cpp
-   Learning-About-Tf2-And-Time-Py
    Learning-About-Tf2-And-Time-Cpp
-   Time-Travel-With-Tf2-Py
    Time-Travel-With-Tf2-Cpp
    Debugging-Tf2-Problems
    Quaternion-Fundamentals
@@ -65,12 +63,12 @@ Learning tf2
 
    This tutorial teaches you how to add an extra fixed frame to tf2.
 
-#. Using time :doc:`(Python) <Learning-About-Tf2-And-Time-Py>` :doc:`(C++) <Learning-About-Tf2-And-Time-Cpp>`.
+#. Using time :doc:`(C++) <Learning-About-Tf2-And-Time-Cpp>`.
 
    This tutorial teaches you to use the timeout in ``lookup_transform`` function to
    wait for a transform to be available on the tf2 tree.
 
-#. Traveling in time :doc:`(Python) <./Time-Travel-With-Tf2-Py>` :doc:`(C++) <./Time-Travel-With-Tf2-Cpp>`.
+#. Traveling in time :doc:`(C++) <./Time-Travel-With-Tf2-Cpp>`.
 
    This tutorial teaches you about advanced time travel features of tf2.
 

source/Tutorials/Intermediate/Tf2/Writing-A-Tf2-Broadcaster-Cpp.rst

@@ -244,6 +244,7 @@ Finally, add the ``install(TARGETS…)`` section so ``ros2 run`` can find your e
 ^^^^^^^^^^^^^^^^^^^^^^^
 
 Now create a launch file for this demo.
+Create a ``launch`` folder in the ``src/learning_tf2_cpp`` directory.
 With your text editor, create a new file called ``turtle_tf2_demo_launch.py`` in the ``launch`` folder, and add the following lines:
 
 .. code-block:: python

source/Tutorials/Intermediate/Tf2/Writing-A-Tf2-Broadcaster-Py.rst

@@ -251,7 +251,7 @@ Add the following line between the ``'console_scripts':`` brackets:
 ^^^^^^^^^^^^^^^^^^^^^^^
 
 Now create a launch file for this demo.
-Create a ``launch`` folder in the ``src/learning_tf2_py`` directory
+Create a ``launch`` folder in the ``src/learning_tf2_py`` directory.
 With your text editor, create a new file called ``turtle_tf2_demo_launch.py`` in the ``launch`` folder, and add the following lines:
 
 .. code-block:: python

source/Tutorials/Intermediate/Tf2/Writing-A-Tf2-Listener-Cpp.rst

@@ -274,7 +274,7 @@ Finally, add the ``install(TARGETS…)`` section so ``ros2 run`` can find your e
 2 Update the launch file
 ^^^^^^^^^^^^^^^^^^^^^^^^
 
-Open the launch file called ``turtle_tf2_demo_launch.py`` with your text editor, add two new nodes to the launch description, add a launch argument, and add the imports.
+Open the launch file called ``turtle_tf2_demo_launch.py`` in the ``src/learning_tf2_cpp/launch`` directory with your text editor, add two new nodes to the launch description, add a launch argument, and add the imports.
 The resulting file should look like:
 
 .. code-block:: python

source/Tutorials/Intermediate/Tf2/Writing-A-Tf2-Listener-Py.rst

@@ -228,7 +228,7 @@ Add the following line between the ``'console_scripts':`` brackets:
 2 Update the launch file
 ^^^^^^^^^^^^^^^^^^^^^^^^
 
-Open the launch file called ``turtle_tf2_demo_launch.py`` with your text editor, add two new nodes to the launch description, add a launch argument, and add the imports.
+Open the launch file called ``turtle_tf2_demo_launch.py`` in the ``src/learning_tf2_py/launch`` directory with your text editor, add two new nodes to the launch description, add a launch argument, and add the imports.
 The resulting file should look like:
 
 .. code-block:: python