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Date: Tue, 21 Mar 2017 14:32:41 +0000 (UTC)
From: "Johan Mabille (JIRA)" <jira@apache.org>
To: dev@arrow.apache.org
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Subject: [jira] [Comment Edited] (ARROW-602) C++: Provide iterator access to
 primitive elements inside a Column/ChunkedArray
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archived-at: Tue, 21 Mar 2017 14:32:48 -0000


    [ https://issues.apache.org/jira/browse/ARROW-602?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15934712#comment-15934712 ] 

Johan Mabille edited comment on ARROW-602 at 3/21/17 2:32 PM:
--------------------------------------------------------------

I thought I would add this interface to numerical arrays for a start, but I agree it might be complicated to go back if we experience any problem in adding this interface to the other array classes in the future.

By the way I guess your first question is adressing the handling of missing values ? Sylvain has done some work on it for xtensor, you might be interested in [https://github.com/QuantStack/xtensor/pull/196].

More generally, what would be the best process for you? I can open a dedicated issue for this topic, so that we can identify all the possible problems and start trying to solve them. Or I can start a draft and we can iterate (or maybe you already started something I can contribute to). I guess this document could go into arrow/cpp/doc, so I may open a PR with an initial draft.


was (Author: johanmabille):
I thought I would add this interface to numerical arrays for a start, but I agree it might be complicated to go back if we experience any problem in adding this interface to the other array classes in the future.

By the way I guess your first question is adressing the handling of missing values ? Sylvain has done some work on it for xtensor, you might be interested in [https://github.com/QuantStack/xtensor/pull/196].

More generally, what would be the best process for you? I can open a dedicated issue for this topic, so that we can identify all the possible problems and start trying to solve them. Or I can start a draft and we can iterate (or maybe you already started something I can contribute to). I guess this document could go into arrow/cpp/doc, so I may open a PR with the initial draft.

> C++: Provide iterator access to primitive elements inside a Column/ChunkedArray
> -------------------------------------------------------------------------------
>
>                 Key: ARROW-602
>                 URL: https://issues.apache.org/jira/browse/ARROW-602
>             Project: Apache Arrow
>          Issue Type: Improvement
>          Components: C++
>            Reporter: Uwe L. Korn
>              Labels: beginner, newbie
>
> Given a ChunkedArray, an Arrow user must currently iterate over all its chunks and then cast them to their types to extract the primitive memory regions to access the values. A convenient way to access the underlying values would be to offer a function that takes a ChunkedArray and returns a C++ iterator over all elements.
> While this may not be the most performant way to access the underlying data, it should have sufficient performance and adds a convenience layer for new users.


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