[
https://issues.apache.org/jira/browse/ARROW-3065?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16626470#comment-16626470
]
David Lee commented on ARROW-3065:
----------------------------------
In pyarrow 0.9.0 the pandas metadata still says float64, but it works..
{code:java}
>>> tbl1.schema
col1: string
col2: string
metadata
--------
{b'pandas': b'{"index_columns": [], "column_indexes": [], "columns": [{"name":'
b' "col1", "field_name": "col1", "pandas_type": "unicode", "numpy_'
b'type": "object", "metadata": null}, {"name": "col2", "field_name'
b'": "col2", "pandas_type": "unicode", "numpy_type": "object", "me'
b'tadata": null}], "pandas_version": "0.23.0"}'}
>>> tbl2.schema
col1: string
col2: string
metadata
--------
{b'pandas': b'{"index_columns": [], "column_indexes": [], "columns": [{"name":'
b' "col1", "field_name": "col1", "pandas_type": "unicode", "numpy_'
b'type": "float64", "metadata": null}, {"name": "col2", "field_nam'
b'e": "col2", "pandas_type": "unicode", "numpy_type": "object", "m'
b'etadata": null}], "pandas_version": "0.23.0"}'}
>>> tbl3.schema
col1: string
col2: string
metadata
--------
{b'pandas': b'{"index_columns": [], "column_indexes": [], "columns": [{"name":'
b' "col1", "field_name": "col1", "pandas_type": "unicode", "numpy_'
b'type": "object", "metadata": null}, {"name": "col2", "field_name'
b'": "col2", "pandas_type": "unicode", "numpy_type": "object", "me'
b'tadata": null}], "pandas_version": "0.23.0"}'}
>>> tbl3[0]
<pyarrow.lib.Column object at 0x7f4055eabc30>
chunk 0: <pyarrow.lib.StringArray object at 0x7f4055e3cf48>
[
'a',
'b',
'c',
'd',
'e',
'f',
'g',
'h'
]
chunk 1: <pyarrow.lib.StringArray object at 0x7f4055e58138>
[
'',
'',
'',
'',
'',
'',
'',
''
]
{code}
In the 0.10.0 example above that can't produce the error tbl3[0] comes back
with:
{code:java}
>>> tbl3[0]
<Column name='col' type=DataType(string)>
[
[
"a",
"b",
"c",
"d",
"e",
"f",
"g",
"h"
],
[
"",
"",
"",
"",
"",
"",
"",
""
]
]
{code}
> [Python] concat_tables() failing from bad Pandas Metadata
> ---------------------------------------------------------
>
> Key: ARROW-3065
> URL: https://issues.apache.org/jira/browse/ARROW-3065
> Project: Apache Arrow
> Issue Type: Bug
> Components: Python
> Affects Versions: 0.10.0
> Reporter: David Lee
> Priority: Major
> Fix For: 0.11.0
>
>
> Looks like the major bug from
> https://issues.apache.org/jira/browse/ARROW-1941 is back...
> After I downgraded from 0.10.0 to 0.9.0, the error disappeared..
> {code:python}
> new_arrow_table = pa.concat_tables(my_arrow_tables)
> File "pyarrow/table.pxi", line 1562, in pyarrow.lib.concat_tables
> File "pyarrow/error.pxi", line 81, in pyarrow.lib.check_status
> pyarrow.lib.ArrowInvalid: Schema at index 2 was different:
> {code}
> In order to debug this I saved the first 4 arrow tables to 4 parquet files
> and inspected the parquet files. The parquet schema is identical, but the
> Pandas Metadata is different.
> {code:python}
> for i in range(5):
> pq.write_table(my_arrow_tables[i], "test" + str(i) + ".parquet")
> {code}
> It looks like a column which contains empty strings is getting typed as
> float64.
> {code:python}
> >>> test1.schema
> HoldingDetail_Id: string
> metadata
> --------
> {b'pandas': b'{"index_columns": [], "column_indexes": [], "columns": [
> {"name": "HoldingDetail_Id", "field_name": "HoldingDetail_Id", "pandas_type":
> "unicode", "numpy_type": "object", "metadata": null},
> >>> test1[0]
> <Column name='HoldingDetail_Id' type=DataType(string)>
> [
> [
> "Z4",
> "SF",
> "J7",
> "W6",
> "L7",
> "Q9",
> "NE",
> "F7",
> >>> test2.schema
> HoldingDetail_Id: string
> metadata
> --------
> {b'pandas': b'{"index_columns": [], "column_indexes": [], "columns": [
> {"name": "HoldingDetail_Id", "field_name": "HoldingDetail_Id", "pandas_type":
> "unicode", "numpy_type": "float64", "metadata": null},
> >>> test2[0]
> <Column name='HoldingDetail_Id' type=DataType(string)>
> [
> [
> "",
> "",
> "",
> "",
> "",
> "",
> "",
> "",
> {code}
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