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https://issues.apache.org/jira/browse/SPARK-14141?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15212563#comment-15212563
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Luke Miner commented on SPARK-14141:
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Is there any way to do this process in chunks: read a chunk of data into a dict
and then append to a pandas dataframe with the pre-specified datatypes?
The big advantage of a pandas dataframe with categorical datatypes is that it
can potentially have a much much smaller memory footprint. However, if
everything is loaded into a huge dict beforehand, there's much less of an
upside.
> Let user specify datatypes of pandas dataframe in toPandas()
> ------------------------------------------------------------
>
> Key: SPARK-14141
> URL: https://issues.apache.org/jira/browse/SPARK-14141
> Project: Spark
> Issue Type: New Feature
> Components: Input/Output, PySpark, SQL
> Reporter: Luke Miner
> Priority: Minor
>
> Would be nice to specify the dtypes of the pandas dataframe during the
> toPandas() call. Something like:
> bq. pdf = df.toPandas(dtypes={'a': 'float64', 'b': 'datetime64', 'c': 'bool',
> 'd': 'category'})
> Since dtypes like `category` are more memory efficient, you could potentially
> load many more rows into a pandas dataframe with this option without running
> out of memory.
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