Give [*joinem*](https://github.com/mmore500/joinem) a try, available via PyPi: `python3 -m pip install joinem`.

*joinem* provides a CLI for fast, flexbile concatenation of tabular data using [polars](https://pola.rs).
I/O is *lazily streamed* in order to give good performance when **working with numerous, large files**.

## Example Usage

Pass input files via stdin and output file as an argument.

ls -1 path/to/*.parquet | python3 -m joinem out.parquet

You can add the `--progress` flag to get a progress bar.

## No-install Containerized Interface

If you are working in a HPC environment, *joinem* can also be conveniently used via [singularity/apptainer](https://apptainer.org).

ls -1 *.pqt | singularity run docker://ghcr.io/mmore500/joinem out.pqt

## Further Information

*joinem* is also compatible with CSV, JSON, and feather file types.
See the project's [README](https://github.com/mmore500/joinem/) for more usage examples and a full command-line interface API listing.

*disclosure*: I am the library author of *joinem*.