[GitHub] [arrow] AlenkaF commented on a change in pull request #12010: ARROW-6001 [Python]: Add from_pylist() and to_pylist() to pyarrow.Table to convert list of records

[GitBox <gi...@apache.org>]

AlenkaF commented on a change in pull request #12010:
URL: https://github.com/apache/arrow/pull/12010#discussion_r778695741



##########
File path: python/pyarrow/table.pxi
##########
@@ -2442,6 +2602,46 @@ def _from_pydict(cls, mapping, schema, metadata):
         raise TypeError('Schema must be an instance of pyarrow.Schema')
 
 
+def _from_pylist(cls, mapping, schema, metadata):
+    """
+    Construct a Table/RecordBatch from list of dictionary of rows.
+
+    Parameters
+    ----------
+    cls : Class Table/RecordBatch
+    mapping : list of dicts of rows
+        A mapping of strings to row values.
+    schema : Schema, default None
+        If not passed, will be inferred from the Mapping values.
+    metadata : dict or Mapping, default None
+        Optional metadata for the schema (if inferred).
+
+    Returns
+    -------
+    Table/RecordBatch
+    """
+
+    arrays = []
+    if schema is None:
+        names = []
+        if mapping:
+            names = list(mapping[0].keys())
+        for n in names:
+            v = [i[n] if n in i else None for i in mapping]
+            arrays.append(asarray(v))
+        return cls.from_arrays(arrays, names, metadata=metadata)
+    else:
+        if isinstance(schema, Schema):
+            for n in schema.names:
+                v = [i[n] if n in i else None for i in mapping]
+                n_type = schema.types[schema.get_field_index(n)]
+                arrays.append(asarray(v, type=n_type))

Review comment:
       The test for the case where schema names are missing from the pylist is added in this PR and it passes:
   https://github.com/apache/arrow/blob/19f212f4f7af0f7720d79a927c4850849da77678/python/pyarrow/tests/test_table.py#L1525-L1538




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