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https://issues.apache.org/jira/browse/ARROW-1491?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16280621#comment-16280621
]
ASF GitHub Bot commented on ARROW-1491:
---------------------------------------
wesm commented on a change in pull request #1387: ARROW-1491: [C++] Add casting
implementations from strings to numbers or boolean
URL: https://github.com/apache/arrow/pull/1387#discussion_r155317738
##########
File path: cpp/src/arrow/compute/kernels/cast.cc
##########
@@ -660,6 +663,100 @@ struct CastFunctor<T, DictionaryType,
}
};
+// ----------------------------------------------------------------------
+// String to Number
+
+template <typename O>
+struct CastFunctor<O, StringType,
+ typename std::enable_if<std::is_base_of<Number,
O>::value>::type> {
+ void operator()(FunctionContext* ctx, const CastOptions& options,
+ const ArrayData& input, ArrayData* output) {
+ using out_type = typename O::c_type;
+ StringArray input_array(input.Copy());
+
+ if (input_array.null_count() > 0) {
+ std::stringstream ss;
+ ss << "Failed to cast NA into " << output->type->ToString();
+ ctx->SetStatus(Status(StatusCode::SerializationError, ss.str()));
+ return;
+ }
+
+ auto out_data = GetMutableValues<out_type>(output, 1);
+
+ std::function<out_type(const std::string&)> cast_func;
+ if (output->type->id() == Type::INT8 || output->type->id() == Type::UINT8)
{
+ cast_func = [](const std::string& s) {
+ return boost::numeric_cast<out_type>(boost::lexical_cast<int>(s));
+ };
+ } else {
+ cast_func = [](const std::string& s) { return
boost::lexical_cast<out_type>(s); };
Review comment:
I think C++11 Lambdas actually incur more overhead than an inlined function.
We should instead introduce an auxiliary numeric cast functor that does this
switch at compile-time (resulting in an inlined function in the inner loop for
all possible types) rather than runtime
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> [C++] Add casting implementations from strings to numbers or boolean
> --------------------------------------------------------------------
>
> Key: ARROW-1491
> URL: https://issues.apache.org/jira/browse/ARROW-1491
> Project: Apache Arrow
> Issue Type: New Feature
> Components: C++
> Reporter: Wes McKinney
> Assignee: Licht Takeuchi
> Labels: pull-request-available
> Fix For: 0.9.0
>
>
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