def vector_memoryview(obj: sexp.SexpVector, sizeof_str: str,
cast_str: str) -> memoryview:
"""
- sizeof_str: type in a string to use with ffi.sizeof()
(for example "int")
- cast_str: type in a string to use with memoryview.cast()
(for example "i")
"""
b = openrlib.ffi.buffer(obj._R_GET_PTR(obj.__sexp__._cdata),
openrlib.ffi.sizeof(sizeof_str) * len(obj))
shape = bufferprotocol.getshape(obj.__sexp__._cdata)
# One could have expected to only need builtin Python
# and do something like
# ```
# mv = memoryview(b).cast(cast_str, shape, order='F')
# ```
# but Python does not handle FORTRAN-ordered arrays without having
# to write C extensions. We have to use numpy.
# TODO: Having numpy a requirement just for this is a problem.
# TODO: numpy needed for memoryview
# (as long as https://bugs.python.org/issue34778 not resolved)
import numpy
a = numpy.frombuffer(b, dtype=cast_str).reshape(shape, order='F')
mv = memoryview(a)
return mv
def __array_interface__(self):
"""Return an `__array_interface__` version 3.
Note that the pointer returned in the items 'data' corresponds to
a memory area under R's memory management and that it will become
invalid once the area once R frees the object. It is safer to keep
the rpy2 object proxying the R object alive for the duration the
pointer is used in Python / numpy."""
return {
'shape': bufferprotocol.getshape(self.__sexp__._cdata),
'typestr': self._NP_TYPESTR,
'strides': bufferprotocol.getstrides(self.__sexp__._cdata),
'data': self._R_GET_PTR(self.__sexp__._cdata),
'version': 3
}
def __array_interface__(self: NPCOMPAT_TYPE) -> dict:
"""Return an `__array_interface__` version 3.
Note that the pointer returned in the items 'data' corresponds to
a memory area under R's memory management and that it will become
invalid once the area once R frees the object. It is safer to keep
the rpy2 object proxying the R object alive for the duration the
pointer is used in Python / numpy."""
shape = bufferprotocol.getshape(self.__sexp__._cdata)
data = openrlib.ffi.buffer(self._R_GET_PTR(self.__sexp__._cdata))
strides = bufferprotocol.getstrides(self.__sexp__._cdata, shape,
self._R_SIZEOF_ELT)
return {
'shape': shape,
'typestr': self._NP_TYPESTR,
'strides': strides,
'data': data,
'version': 3
}
def memoryview(self) -> memoryview:
b = _rinterface.ffi.buffer(openrlib._REAL(self.__sexp__._cdata),
openrlib.ffi.sizeof('double') * len(self))
shape = bufferprotocol.getshape(self.__sexp__._cdata)
mv = memoryview(b).cast('d', shape)
return mv
def memoryview(self):
b = _rinterface.ffi.buffer(openrlib._LOGICAL(self.__sexp__._cdata),
openrlib.ffi.sizeof('int') * len(self))
shape = bufferprotocol.getshape(self.__sexp__._cdata)
mv = memoryview(b).cast('i', shape)
return mv
