Add support for reading/writing parquet files with fastparquet#253
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Add support for reading/writing parquet files with fastparquet#253
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Test alternate approach to supporting parquet I/O using the fastparquet library instead of pyarrow. Both libraries should produce similar results, but fastparquet is smaller and focused solely on this format.
This was referenced May 23, 2025
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Description of proposed changes
We need support for reading/writing parquet files to prepare submissions to the SARS-CoV-2 variant hub [1]. pandas supports two backends for parquet I/O [2] including pyarrow and fastparquet. The pyarrow library provides a more comprehensive set of tools for the Arrow spec [3], while fastparquet is defined to provide a minimal library for the parquet format.
I've opted for the smaller fastparquet library here, since it provides exactly the functionality we need for an additional 4 MB of Docker image size. The pyarrow library will eventually be a required dependency for pandas [4], so we may eventually need to include to that library. However, pyarrow adds 40 MB to the Docker image size most of which is functionality we don't need.
[1] nextstrain/forecasts-ncov#132
[2] https://pandas.pydata.org/pandas-docs/stable/user_guide/io.html#io-parquet
[3] https://arrow.apache.org/docs/cpp/user_guide.html
[4] https://pandas.pydata.org/pdeps/0010-required-pyarrow-dependency.html
Related issue(s)
Alternative to #252
Required for nextstrain/forecasts-ncov#132
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