Update doc files to match recent fixes for latest pyarrow/polars. (#22)

Author: lgautier

doc/notebooks/faster-rpy2-conversion.rst

@@ -85,7 +85,7 @@ custom converter for :mod:`rpy2` is done in few lines of code.
        ...: # We build a custom converter that is the default converter
        ...: # for ipython/jupyter shipping with rpy2, to which we add
        ...: # rules for Arrow + pandas we just made.
-       ...: conv = rpy2.ipython.rmagic.converter + conv
+       ...: conv = rpy2.ipython.rmagic.default.converter + conv
 
 Our custom converter ``conv`` can be specified as a parameter to
 ``%%R``:
@@ -118,7 +118,7 @@ It is also possible to only convert to an Arrow data structure.
        ...:     pa_tbl = pyarrow.Table.from_pandas(dataf)
        ...:     return pyra.converter.py2rpy(pa_tbl)
        ...:   
-       ...: conv2 = rpy2.ipython.rmagic.converter + conv2
+       ...: conv2 = rpy2.ipython.rmagic.default.converter + conv2
 
 .. ipython::
 

rpy2_arrow/arrow.py

@@ -125,7 +125,9 @@ def pyarrow_to_r_recordbatchreader(
 
     stream_ptr = ffi.new('struct ArrowArrayStream*')
     obj._export_to_c(_c_ptr_to_int(stream_ptr))
-    return rarrow.RecordBatchReader['import_from_c'](_rarrow_ptr(stream_ptr))
+    with robjects.default_converter.context():
+        r_ptr = _rarrow_ptr(stream_ptr)
+        return rarrow.RecordBatchReader['import_from_c'](r_ptr)
 
 
 def rarrow_to_py_recordbatchreader(