I think the nodes directory should be directly under the package rather than src folder. According to REP8-Style Guide for Python Code,
"The recommended layout is to put all
of your package's importable Python
code in the src folder of your package
and in a "Python package" with the
same name as your package. In this
case a "Python package" is a folder
which contains a __init__.py file,
indicating that the folder contains
additional Python packages and
modules."
The src folder thus should store Python packages and modules if you want to make them importable into other ROS packages.
Also, does it matter where this file
is located within the package? I've
seen other places where Python files
are in a dir called scripts as opposed
to src.
As far as I know, technically, it does not matter where the file is located within the package since rosrun is able to find the location of the executable for a package recursively (rosrun-source code). So as long as your executable file- python script is in the directory of your ROS package (under src in the catkin workspace, since catkin_make command only looks for packages under src dir) and your local workspace is properly sourced, rosrun should be able to find that executable.
However, conventionally, according to an excerpt from REP8-Style Guide for Python Code,
"We distinguish between "nodes" and
"scripts" for clarity to users. Nodes
are executable Python files that
conform to the ROS node API. Scripts
are executable Python files that do
not conform to the ROS node API."
Aslo from Installing Python scripts and modules
“Standard ROS practice is to place all
executable Python programs in a
package subdirectory named nodes/ or
scripts/. Their usage is the same, the
two names distinguish ROS nodes from
other executable Python scripts.”
So I think, conventionally, an executable python script that contains ROS nodes should go to nodes folder.
I guess distinctions are the convention and good practices to make your package structure more clear.
I think the rationale for ROS users putting python scripts into scripts folder is based on the common practice for python packages. In Python, people usually put top-level executable scripts in the scripts/ (or bin/) directory and place python packages and modules (used by scripts) into the src/ directory. As for the distinction between nodes and scripts in ROS, I don't really know if it's a horrible practice to not separate nodes and scripts. Tbh, personally, I've seldom seen nodes folder. My guess is perhaps ROS users generally consider nodes/ as a subset of scripts/, since scripts are any executable python scripts for any purpose.
