dhruv9vats commented on a change in pull request #12162:
URL: https://github.com/apache/arrow/pull/12162#discussion_r785455620
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File path: cpp/src/arrow/compute/kernels/scalar_nested.cc
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@@ -429,6 +430,97 @@ const FunctionDoc make_struct_doc{"Wrap Arrays into a
StructArray",
{"*args"},
"MakeStructOptions"};
+struct MapArrayLookupFunctor {
+ static Status ExecMapArray(KernelContext* ctx, const ExecBatch& batch,
Datum* out) {
+ const auto& options = OptionsWrapper<MapArrayLookupOptions>::Get(ctx);
+
+ MapArray map_array(batch[0].array());
+
+ // Offset differences will tell the number of Strcut = {key, value} pairs
+ // present in the current list.
+ // const std::shared_ptr<arrow::Buffer> offsets =
map_array.value_offsets();
+
+ std::shared_ptr<arrow::Array> keys = map_array.keys();
+ std::shared_ptr<arrow::Array> items = map_array.items();
+
+ const auto& query_key = options.query_key;
+ const auto& occurence = options.occurence;
+
+ std::unique_ptr<ArrayBuilder> builder;
+ RETURN_NOT_OK(
+ MakeBuilder(ctx->memory_pool(), map_array.map_type()->item_type(),
&builder));
+
+ int32_t last_key_idx_checked = 0;
+
+ // aka, number of {key, value} pairs in the current map
+ int32_t list_struct_len;
+ bool found_one_key = false;
+ for (int32_t map_array_idx = 0; map_array_idx < map_array.length();
++map_array_idx) {
+ // Number of Struct('s) = {key, value} in the list at the current index
+ list_struct_len = map_array.value_length(map_array_idx);
+ for (int32_t key_idx_to_check = last_key_idx_checked;
+ key_idx_to_check < last_key_idx_checked + list_struct_len;
+ ++key_idx_to_check) {
+ ARROW_ASSIGN_OR_RAISE(std::shared_ptr<Scalar> key,
+ keys->GetScalar(key_idx_to_check));
+ if (key->Equals(*query_key)) {
+ std::cout << "Key being checked: " << key->ToString() << "\n";
+ ARROW_ASSIGN_OR_RAISE(std::shared_ptr<Scalar> item,
+ items->GetScalar(key_idx_to_check));
+ std::cout << "Value at key: " << item->ToString() << "\n";
+ ARROW_ASSIGN_OR_RAISE(auto value,
+
item->CastTo(map_array.map_type()->item_type()));
+
+ std::cout << "Item being appended: " << value->ToString() << "\n";
+ RETURN_NOT_OK(builder->AppendScalar(*value));
+
+ if (occurence == MapArrayLookupOptions::First) {
+ found_one_key = true;
+ break;
+ }
+ }
+ }
+ if (found_one_key && occurence == MapArrayLookupOptions::First) break;
Review comment:
Using this in conjunction with the condition above to break out of
nested `for` loops if `Occurence::First` is used. As this currently is, this
will break out when the first key is encountered, regardless of whether there
are matching keys in _other_ `Lists`. Is this what we want?
If instead _all_ `First` keys (and its item) from *each* `List` is needed,
removing this condition will (I hope) suffice.
There was also a mention of returning a different `DataType` when `First` is
used as opposed to `All`, so how does this all work?
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