[
https://issues.apache.org/jira/browse/ARROW-10406?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17259609#comment-17259609
]
Joris Van den Bossche commented on ARROW-10406:
-----------------------------------------------
I agree with [~npr] that this is a typical use case that should work out of the
box. If the IPC file format does not support different dictionaries, I would
expect that we unify the dictionaries before writing.
(that's also what we eg do on conversion to pandas in {{to_pandas()}}, and
probably in R as well when converting to a DataFrame with factors?)
> [Format] Support dictionary replacement in the IPC file format
> --------------------------------------------------------------
>
> Key: ARROW-10406
> URL: https://issues.apache.org/jira/browse/ARROW-10406
> Project: Apache Arrow
> Issue Type: Wish
> Components: Format
> Reporter: Neal Richardson
> Priority: Major
>
> I read a big (taxi) csv file and specified that I wanted to dictionary-encode
> some columns. The resulting Table has ChunkedArrays with 1604 chunks. When I
> go to write this Table to the IPC file format (write_feather), I get an
> error:
> {code}
> Invalid: Dictionary replacement detected when writing IPC file format.
> Arrow IPC files only support a single dictionary for a given field accross
> all batches.
> {code}
> I can write this to Parquet and read it back in, and the roundtrip of the
> data is correct. We should be able to do this in IPC too.
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
