zanmato1984 commented on code in PR #44394:
URL: https://github.com/apache/arrow/pull/44394#discussion_r1879217436
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cpp/src/arrow/compute/api_vector.h:
##########
@@ -705,5 +737,52 @@ Result<std::shared_ptr<Array>> PairwiseDiff(const Array&
array,
bool check_overflow = false,
ExecContext* ctx = NULLPTR);
+/// \brief Return the inverse permutation of the given indices.
+///
+/// For indices[i] = x, inverse_permutation[x] = i. And inverse_permutation[x]
= null if x
+/// does not appear in the input indices. For indices[i] = x where x < 0 or x
> max_index,
+/// it is ignored. If multiple indices point to the same value, the last one
is used.
+///
+/// For example, with indices = [null, 0, 3, 2, 4, 1, 1], the inverse
permutation is
+/// [1, 6, 3] if max_index = 2,
+/// [1, 6, 3, 2, 4, null, null] if max_index = 6.
+///
+/// \param[in] indices array-like indices
+/// \param[in] options configures the max index and the output type
+/// \param[in] ctx the function execution context, optional
+/// \return the resulting inverse permutation
+///
+/// \since 19.0.0
+/// \note API not yet finalized
+ARROW_EXPORT
+Result<Datum> InversePermutation(
+ const Datum& indices,
+ const InversePermutationOptions& options =
InversePermutationOptions::Defaults(),
+ ExecContext* ctx = NULLPTR);
+
+/// \brief Scatter the values into specified positions according to the
indices.
+///
+/// For indices[i] = x, output[x] = values[i]. And output[x] = null if x does
not appear
+/// in the input indices. For indices[i] = x where x < 0 or x > max_index,
values[i]
+/// is ignored. If multiple indices point to the same value, the last one is
used.
Review Comment:
OK. This is quite reasonable. I'll update.
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