start = time.time()

result = (
    pl.scan_csv('large_sales_data.csv')
    .with_columns([
        (pl.col('sales') * pl.col('quantity') * (1 - 0.075)).alias('net_revenue')
    ])
    .with_columns([
        pl.when(pl.col('net_revenue') > 50000)
        .then(pl.lit('high'))
        .otherwise(pl.lit('low'))
        .alias('order_flag')
    ])
    .group_by('region')
    .agg(pl.col('net_revenue').sum())
    .collect()
)

end = time.time()
print(f"Polars Lazy runtime: {end - start:.2f} seconds")
print(result)