[jira] [Created] (ARROW-10133) parquet Int64 col cast to float64 on load in pandas

["Jacqueline Nolis (Jira)" <ji...@apache.org>]

Jacqueline Nolis created ARROW-10133:
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             Summary: parquet Int64 col cast to float64 on load in pandas
                 Key: ARROW-10133
                 URL: https://issues.apache.org/jira/browse/ARROW-10133
             Project: Apache Arrow
          Issue Type: Bug
          Components: Python
    Affects Versions: 0.17.1
            Reporter: Jacqueline Nolis
         Attachments: example-failed-int64.parquet

Under certain conditions a saved parquet table with a column that is Int64 and all NA seems to be cast to a float64 with all NaN on load. The desired behavior is to have it stay as Int64. Attached is a table where said issue occurs: the second column here should be a int64 but is being loaded as a float64 in Pandas.

 

Interestingly, it seems to be correctly interpreting the column as a Int64 when loading in R, so perhaps its only a Pandas issue.

 
import pyarrow.parquet as pq
import boto3
import pandas as pd
import io
obj = boto3.client('s3').get_object(Bucket="...", Key='...') # file attached to ticket
x = pq.read_table(io.BytesIO(obj['Body'].read()))
y = x.to_pandas() # this is where the undesired int64 to a float64 cast occurs

# >>> x
# pyarrow.Table
# product_id: string
# cost: int64
# name: string

# >>> y.dtypes
# product_id object
# cost float64
# name object
# dtype: object



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