Enhance iDynTree from / to Python mapping and add proper NumPy support

.github/workflows/ci.yml

@@ -73,8 +73,10 @@ jobs:
       if: contains(matrix.os, 'ubuntu')
       run: |
         sudo apt-get update
-        sudo apt-get install git build-essential cmake libace-dev coinor-libipopt-dev libeigen3-dev swig qtbase5-dev qtdeclarative5-dev qtmultimedia5-dev libqt5charts5-dev \
-                             libxml2-dev liboctave-dev python-dev valgrind libassimp-dev
+        sudo apt-get install \
+            git build-essential cmake libace-dev coinor-libipopt-dev libeigen3-dev swig \
+            qtbase5-dev qtdeclarative5-dev qtmultimedia5-dev libqt5charts5-dev \
+            libxml2-dev liboctave-dev python-dev python3-numpy valgrind libassimp-dev
 
     - name: Cache Source-based Dependencies
       id: cache-source-deps

CHANGELOG.md

@@ -11,6 +11,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Added a new CMake option `IDYNTREE_COMPILES_TOOLS` to disable compilation of iDynTree tools.
 - Added a `KinDynComputations::getCentroidalTotalMomentumJacobian()` method (https://github.com/robotology/idyntree/pull/706)
 - iDynTree now supports build compiled as a shared library also on Windows.
+- When used in Python, new iDynTree objects can be constructed from generic iterable objects and NumPy arrays (`*.FromPython`),
+  and existing objects can be converted to NumPy arrays (`*.toNumPy`) (https://github.com/robotology/idyntree/pull/726).
 
 ### Fixed
 - Fixed bug in `yarprobotstatepublisher` that caused segmentation fault each time an unknown joint name was read from the input joint states topic (https://github.com/robotology/idyntree/pull/719)
@@ -19,12 +21,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Changed
 - By default  iDynTree is compiled as a shared library also on Windows. The `BUILD_SHARED_LIBS` CMake variable can be used to
   control if iDynTree is built as a shared or a static library.
+- The Python method `*.fromPyList` is replaced by `*.FromPython` (https://github.com/robotology/idyntree/pull/726).
 
 ### Removed 
 - Remove the CMake option IDYNTREE_USES_KDL and all the classes available when enabling it. They were deprecated in iDynTree 1.0 .
 - Remove the semantics related classes. They were deprecated in iDynTree 1.0 .
 - Remove unnecessary warning messages from [ModelSensorsTransformers.cpp](https://github.com/robotology/idyntree/blob/master/src/sensors/src/ModelSensorsTransformers.cpp) and [URDFDocument.cpp](https://github.com/robotology/idyntree/blob/master/src/model_io/urdf/src/URDFDocument.cpp) (see [PR 718](https://github.com/robotology/idyntree/pull/718))
-
+- Python2 will not be maintained past 2020 and its support has been dropped (https://github.com/robotology/idyntree/pull/726).
+- Remove the need to call `iDynTree.init_helpers()` and `iDynTree.init_numpy_helpers()` from Python (https://github.com/robotology/idyntree/pull/726).
 
 ## [Unreleased]
 

bindings/CMakeLists.txt

@@ -13,7 +13,7 @@ option(IDYNTREE_GENERATE_MATLAB "Enable if you have the experimental version of
 find_package(SWIG)
 # It is possible to compile matlab/octave bindings without using SWIG
 if(SWIG_FOUND OR IDYNTREE_USES_MATLAB OR IDYNTREE_USES_OCTAVE)
-    include(UseSWIG)
+    include(${SWIG_USE_FILE})
 
     set_source_files_properties(iDynTree.i PROPERTIES CPLUSPLUS ON)
 

bindings/python/CMakeLists.txt

@@ -1,39 +1,37 @@
 set(CMAKE_SWIG_FLAGS "-Wextra;-module;iDynTree;-threads")
-set(IDYNTREE_USES_PYTHON_VERSION "" CACHE STRING "Specify python version to use" )
 
-find_package(PythonInterp ${IDYNTREE_USES_PYTHON_VERSION} REQUIRED)
-set(IDYNTREE_USES_PYTHON_VERSION_ARGS)
-  if(NOT IDYNTREE_USES_PYTHON_VERSION)
-     set (IDYNTREE_USES_PYTHON_VERSION ${PYTHON_VERSION_STRING})
-  endif()
+find_package(Python3 COMPONENTS Interpreter Development NumPy REQUIRED)
+message(STATUS "Using Python: ${Python3_EXECUTABLE}")
 
-find_package(PythonLibs ${IDYNTREE_USES_PYTHON_VERSION} EXACT)
-include_directories(${PYTHON_INCLUDE_PATH})
-link_libraries(${PYTHON_LIBRARY})
+set_source_files_properties(../iDynTree.i PROPERTIES CPLUSPLUS ON)
 
-## in Windows it seems necessary to declare explictly the link_directory
-if(WIN32)
-  get_filename_component(PYTHON_DIR ${PYTHON_LIBRARY} PATH)
-  link_directories(${PYTHON_DIR})
-endif()
+swig_add_library(iDynTree_python
+    TYPE SHARED
+    LANGUAGE python
+    SOURCES ../iDynTree.i)
 
-set(target_name iDynTree_python)
+set(target_name ${SWIG_MODULE_iDynTree_python_REAL_NAME})
 
-set_source_files_properties(../iDynTree.i PROPERTIES CPLUSPLUS ON)
-swig_add_module(${target_name} python ../iDynTree.i)
-set_target_properties(_${target_name} PROPERTIES OUTPUT_NAME "_iDynTree")
-set_target_properties(_${target_name} PROPERTIES LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib/python)
+target_link_libraries(${target_name} PUBLIC Python3::Python Python3::NumPy)
+set_target_properties(${target_name} PROPERTIES
+    OUTPUT_NAME "_iDynTree"
+    LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib/python)
+
+set_property(
+    TARGET ${target_name}
+    PROPERTY SWIG_DEPENDS
+    python.i numpy.i)
 
 # installation path is determined reliably on most platforms using distutils
-execute_process(COMMAND ${PYTHON_EXECUTABLE}
+execute_process(COMMAND ${Python3_EXECUTABLE}
     -c "from distutils import sysconfig; print(sysconfig.get_python_lib(1,0,prefix=''))"
     OUTPUT_VARIABLE PYTHON_INSTDIR)
 string(STRIP ${PYTHON_INSTDIR} PYTHON_INSTDIR)
        install(FILES ${CMAKE_CURRENT_BINARY_DIR}/iDynTree.py DESTINATION ${PYTHON_INSTDIR} )
-       install(TARGETS _${target_name} DESTINATION ${PYTHON_INSTDIR} )
+       install(TARGETS ${target_name} DESTINATION ${PYTHON_INSTDIR} )
 
 if(WIN32)
-    set_target_properties(_${target_name} PROPERTIES SUFFIX ".pyd")
+    set_target_properties(${target_name} PROPERTIES SUFFIX ".pyd")
 endif(WIN32)
 
 # if compile tests execute also python tests