flowview

Visual data pipeline debugger for Polars. Stop print-debugging your pipelines.

Install

pip install flowview

Usage

Add @fv.trace to any function that transforms a Polars DataFrame. flowview traces every method call and renders a visual flow in your terminal.

import polars as pl
import flowview as fv

@fv.trace
def process(df: pl.DataFrame) -> pl.DataFrame:
    return (
        df.filter(pl.col("status") == "active")
          .with_columns((pl.col("price") * pl.col("quantity")).alias("revenue"))
          .group_by("category")
          .agg(pl.col("revenue").sum().alias("total_revenue"))
          .sort("total_revenue", descending=True)
    )

.pipe() chains are also supported:

@fv.trace
def process(df: pl.DataFrame) -> pl.DataFrame:
    return df.pipe(clean).pipe(filter_active).pipe(add_revenue)

Each step shows:

• Row counts with diffs
• Schema changes (added/removed columns)
• Sample data at each transformation
• Execution time per step

Options

@fv.trace(sample_rows=3, show_sample=True, show_schema=True)
def process(df):
    ...