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https://issues.apache.org/jira/browse/ARROW-1950?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16304052#comment-16304052
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Phillip Cloud edited comment on ARROW-1950 at 12/26/17 10:59 PM:
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There are a couple issues here:

1. We're mapping arrow null types to float64 because of nans, but I don't think 
that's correct since null is both tye type of typeless missing values _and_ the 
type of empty things, including the value type for empty lists and maps. Really 
the {{pandas_type}} should be {{'empty'}}.
2. The C++ {{table_to_blocks}} function doesn't actually support null types


was (Author: cpcloud):
There are a couple issues here:

1. We're mapping arrow null types to float64 because of nans, but I don't think 
that's correct since null is both tye type of typeless missing values _and_ the 
type of empty things, including the value type for empty lists and maps. Really 
the {{pandas_type}} should be {{'empty'}}.
2. The C++ table_to_blocks function doesn't actually support null types

> [Python] pandas_type in pandas metadata incorrect for List types
> ----------------------------------------------------------------
>
>                 Key: ARROW-1950
>                 URL: https://issues.apache.org/jira/browse/ARROW-1950
>             Project: Apache Arrow
>          Issue Type: Bug
>          Components: Python
>            Reporter: Wes McKinney
>             Fix For: 0.9.0
>
>
> see https://github.com/pandas-dev/pandas/pull/18201#issuecomment-353042438



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