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https://issues.apache.org/jira/browse/ARROW-1886?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16407176#comment-16407176
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ASF GitHub Bot commented on ARROW-1886:
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cpcloud commented on a change in pull request #1768: ARROW-1886: [C++/Python]
Flatten struct columns in table
URL: https://github.com/apache/arrow/pull/1768#discussion_r175943054
##########
File path: cpp/src/arrow/type.cc
##########
@@ -42,6 +42,21 @@ std::shared_ptr<Field> Field::RemoveMetadata() const {
return std::make_shared<Field>(name_, type_, nullable_);
}
+std::vector<std::shared_ptr<Field>> Field::Flatten() const {
+ std::vector<std::shared_ptr<Field>> flattened;
+ if (type_->id() == Type::STRUCT) {
+ for (const auto& child : type_->children()) {
+ auto flattened_child = std::make_shared<Field>(*child);
+ flattened.push_back(flattened_child);
+ flattened_child->name_.insert(0, name() + ".");
Review comment:
This is going to appear strange IMO if the name has a period or space or
something other than variable name. This is kind of a can of worms without
[`std::quoted`](http://en.cppreference.com/w/cpp/io/manip/quoted) (available in
>=C++14)
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> [Python] Add function to "flatten" structs within tables
> --------------------------------------------------------
>
> Key: ARROW-1886
> URL: https://issues.apache.org/jira/browse/ARROW-1886
> Project: Apache Arrow
> Issue Type: Improvement
> Components: Python
> Reporter: Wes McKinney
> Assignee: Antoine Pitrou
> Priority: Major
> Labels: pull-request-available
> Fix For: 0.10.0
>
>
> See discussion in https://issues.apache.org/jira/browse/ARROW-1873
> When a user has a struct column, it may be more efficient to flatten the
> struct into multiple columns of the form {{struct_name.field_name}} for each
> field in the struct. Then when you call {{to_pandas}}, Python dictionaries do
> not have to be created, and the conversion will be much more efficient
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