pitrou commented on a change in pull request #7614:
URL: https://github.com/apache/arrow/pull/7614#discussion_r449080783
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File path: r/src/array_from_vector.cpp
##########
@@ -351,15 +351,20 @@ std::shared_ptr<Array>
MakeFactorArrayImpl(Rcpp::IntegerVector_ factor,
std::shared_ptr<Array> MakeFactorArray(Rcpp::IntegerVector_ factor,
const std::shared_ptr<arrow::DataType>&
type) {
- SEXP levels = factor.attr("levels");
- int n = Rf_length(levels);
- if (n < 128) {
+ auto* dict_type = checked_cast<arrow::DictionaryType*>(type.get());
+ auto index_type = dict_type->index_type();
+ if (index_type->Equals(int8())) {
Review comment:
Faster if written as `index_type->id() == Type::INT8`. You may or may
not bother, depending on how important this function is.
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