GH-37145: [Python] support boolean columns with bitsize 1 in from_dat…

…aframe (#37975) ### Rationale for this change Bit-packed booleans are currently not supported in the `from_dataframe` of the Dataframe Interchange Protocol. Note: We currently represent booleans in the pyarrow implementation as `uint8` which will also need to be changed in a follow-up PR (see data-apis/dataframe-api#227). ### What changes are included in this PR? This PR adds the support for bit-packed booleans when consuming a dataframe interchange object. ### Are these changes tested? Only locally, currently! * Closes: #37145 Lead-authored-by: AlenkaF <[email protected]> Co-authored-by: Alenka Frim <[email protected]> Signed-off-by: AlenkaF <[email protected]>
apache · Oct 5, 2023 · 161510e · 161510e
1 parent f7530de
commit 161510e
Showing 1 changed file with 9 additions and 4 deletions.
diff --git a/python/pyarrow/interchange/from_dataframe.py b/python/pyarrow/interchange/from_dataframe.py
@@ -54,7 +54,8 @@
     DtypeKind.FLOAT: {16: pa.float16(),
                       32: pa.float32(),
                       64: pa.float64()},
-    DtypeKind.BOOL: {8: pa.uint8()},
+    DtypeKind.BOOL: {1: pa.bool_(),
+                     8: pa.uint8()},
     DtypeKind.STRING: {8: pa.string()},
 }
 
@@ -232,19 +233,23 @@ def bool_column_to_array(
     -------
     pa.Array
     """
-    if not allow_copy:
+    buffers = col.get_buffers()
+    size = buffers["data"][1][1]
+
+    # If booleans are byte-packed a copy to bit-packed will be made
+    if size == 8 and not allow_copy:
         raise RuntimeError(
             "Boolean column will be casted from uint8 and a copy "
             "is required which is forbidden by allow_copy=False"
         )
 
-    buffers = col.get_buffers()
     data_type = col.dtype
     data = buffers_to_array(buffers, data_type,
                             col.size(),
                             col.describe_null,
                             col.offset)
-    data = pc.cast(data, pa.bool_())
+    if size == 8:
+        data = pc.cast(data, pa.bool_())
 
     return data