jorisvandenbossche commented on code in PR #13989:
URL: https://github.com/apache/arrow/pull/13989#discussion_r956994361
##########
python/pyarrow/array.pxi:
##########
@@ -2478,6 +2478,55 @@ cdef class DictionaryArray(Array):
return self._indices
+ @staticmethod
+ def from_buffers(DataType type, int64_t length, buffers, dictionary,
+ int64_t null_count=-1, int64_t offset=0,
memory_pool=None):
+ """
+ Construct a DictionaryArray from buffers.
+
+ type : pyarrow.DataType
Review Comment:
```suggestion
Parameters
----------
type : pyarrow.DataType
```
##########
python/pyarrow/array.pxi:
##########
@@ -2478,6 +2478,55 @@ cdef class DictionaryArray(Array):
return self._indices
+ @staticmethod
+ def from_buffers(DataType type, int64_t length, buffers, dictionary,
+ int64_t null_count=-1, int64_t offset=0,
memory_pool=None):
+ """
+ Construct a DictionaryArray from buffers.
+
+ type : pyarrow.DataType
Review Comment:
And can you also add a "Returns" section?
##########
python/pyarrow/tests/test_array.py:
##########
@@ -725,6 +725,13 @@ def test_struct_array_from_chunked():
pa.StructArray.from_arrays([chunked_arr], ["foo"])
+def test_dictionary_from_buffers():
+ a = pa.array(["one", "two", "three", "two", "one"]).dictionary_encode()
+ b = pa.DictionaryArray.from_buffers(
+ a.type, len(a), a.indices.buffers(), a.dictionary)
+ assert a == b
+
Review Comment:
Maybe add a test with an offset as well?
##########
python/pyarrow/array.pxi:
##########
@@ -2478,6 +2478,55 @@ cdef class DictionaryArray(Array):
return self._indices
+ @staticmethod
+ def from_buffers(DataType type, int64_t length, buffers, dictionary,
+ int64_t null_count=-1, int64_t offset=0,
memory_pool=None):
+ """
+ Construct a DictionaryArray from buffers.
+
+ type : pyarrow.DataType
+ length : int
+ The number of values in the array.
+ buffers : List[Buffer]
+ The buffers backing this array.
+ dictionary : pyarrow.Array, ndarray or pandas.Series
+ The array of values referenced by the indices.
+ null_count : int, default -1
+ The number of null entries in the array. Negative value means that
+ the null count is not known.
+ offset : int, default 0
+ The array's logical offset (in values, not in bytes) from the
+ start of each buffer.
+ memory_pool : MemoryPool, default None
+ For memory allocations, if required, otherwise uses default pool.
+ """
+ cdef:
+ Array _dictionary
+ vector[shared_ptr[CBuffer]] c_buffers
+ shared_ptr[CDataType] c_type
+ shared_ptr[CArrayData] c_data
+ shared_ptr[CArray] c_result
+
+ for buf in buffers:
+ c_buffers.push_back(pyarrow_unwrap_buffer(buf))
+
+ if isinstance(dictionary, Array):
+ _dictionary = dictionary
+ else:
+ _dictionary = array(dictionary, memory_pool=memory_pool)
Review Comment:
Given that this is a "power-user" method anyway, I think it is maybe fine to
require an Array here for the dictionary (for the Buffers we also only accept
actual buffers, and that would avoid needing to add the `memory_pool` keyword,
and avoid having to test this, which isn't the case at the moment)
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