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From "Uwe L. Korn (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (ARROW-229) C++: Add Helper to cast primitive arrays
Date Tue, 15 Nov 2016 21:45:58 GMT

     [ https://issues.apache.org/jira/browse/ARROW-229?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Uwe L. Korn updated ARROW-229:
------------------------------
    Description: In some situations, you want to cast the data in a PrimitiveArray to a different
(but similar) data type, e.g. from {{uint32_t}} to {{int32_t}} or {{uint32_t}} to {{uint8_t}}.
This can either be done by reinterpreting the data or needs to involve a copy if the size
of the underlying type changes. There is already an implementation for this in {{parquet-cpp}}
that could be pulled out into Arrow: https://github.com/apache/parquet-cpp/blob/9a0407e684c0a6299d0e6ab98c11c1162915c0ee/src/parquet/arrow/writer.cc#L71
 (was: Depending on the type conversion, this is either just a reinterpret_cast on the data
pointer or involves a data copy.)

> C++: Add Helper to cast primitive arrays
> ----------------------------------------
>
>                 Key: ARROW-229
>                 URL: https://issues.apache.org/jira/browse/ARROW-229
>             Project: Apache Arrow
>          Issue Type: New Feature
>          Components: C++
>            Reporter: Uwe L. Korn
>              Labels: newbie
>
> In some situations, you want to cast the data in a PrimitiveArray to a different (but
similar) data type, e.g. from {{uint32_t}} to {{int32_t}} or {{uint32_t}} to {{uint8_t}}.
This can either be done by reinterpreting the data or needs to involve a copy if the size
of the underlying type changes. There is already an implementation for this in {{parquet-cpp}}
that could be pulled out into Arrow: https://github.com/apache/parquet-cpp/blob/9a0407e684c0a6299d0e6ab98c11c1162915c0ee/src/parquet/arrow/writer.cc#L71



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