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Posted to github@arrow.apache.org by GitBox <gi...@apache.org> on 2021/01/11 09:30:50 UTC

[GitHub] [arrow] kiszk commented on a change in pull request #9142: ARROW-11193: [Java][Documentation] Add Java ListVector Documentation

kiszk commented on a change in pull request #9142:
URL: https://github.com/apache/arrow/pull/9142#discussion_r554915754



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File path: docs/source/java/vector.rst
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@@ -217,6 +217,55 @@ to be declared is that writer/reader is not as efficient as direct access
       }
     }
 
+Building ListVector
+==================
+
+A :class:`ListVector` is a vector that holds a list of values for each index. Working with one you need to handle the same steps as mentioned above (create > allocate > mutate > set value count > access > clear), but the details of how you accomplish this are slightly different since you need to both create the vector and set the list of values for each index.
+
+For example, the code below shows how to build a :class:`ListVector` of int's using the writer :class:`UnionListWriter`. We build a vector from 0 to 10 and each index contains a list with increasing values [[0, 0, 0, 0, 0], [0, 1, 2, 3, 4], [0, 2, 4, 6, 8], …, [0, 9, 18, 27, 36]].

Review comment:
       nit: `0 to 10` -> `0 to 9`  ?




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