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https://issues.apache.org/jira/browse/ARROW-3263?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16912749#comment-16912749
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Wes McKinney commented on ARROW-3263:
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Circling back on this discussion from a year ago.
Now that we have {{arrow::ExtensionType}} in C++, technically we could
introduce containers for R data that has not been serialized to one of the
built-in Arrow types. I'm not sure what you would do with such data, but
technically it is now possible to faithfully transport unmodified R data end to
end through Arrow's IPC / RPC machinery
> [R] Use R sentinel values for missingness in addition to bitmask
> ----------------------------------------------------------------
>
> Key: ARROW-3263
> URL: https://issues.apache.org/jira/browse/ARROW-3263
> Project: Apache Arrow
> Issue Type: Improvement
> Components: Format
> Reporter: Gabriel Becker
> Priority: Major
>
> R uses sentinal values to indicate missingness within Atomic vectors (read
> arrays in Arrow parlance, AFAIK).
> Currently according to [~wesmckinn], the current value in the array in memory
> is undefined if the bitmap indicating missingness is set to 1.
> This will force R to copy and modify data whenever adopting Arrow data which
> has missingness present as a native vector.
> If the value were written to the relevant sentinal values (INT_MIN for 32 bit
> integers, and NaN with payload 1954 for double precision floats) _in addition
> to_ the bit mask, then R would be able to use Arrow as intended while not
> breaking any other systems.
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