Writing Data

Common examples for writing tabular data in Fused.

Geospatial data?

For geospatial formats (GeoParquet, GeoTIFF, etc.), see Writing Geospatial Data.

CSV

@fused.udf
def udf():
    import pandas as pd
    
    df = pd.DataFrame({'col1': [1, 2], 'col2': [3, 4]})
    
    # Write to Fused managed storage
    df.to_csv("fd://my-data/output.csv", index=False)
    
    return "Saved!"

Parquet

Parquet is the recommended format for tabular data - it's columnar, compressed, and fast.

@fused.udf
def udf(path: str = "s3://fused-sample/demo_data/housing_2024.csv"):
    import pandas as pd
    
    df = pd.read_csv(path)
    df['price_per_area'] = round(df['price'] / df['area'], 2)
    
    # Save to your Fused bucket
    username = fused.api.whoami()['handle']
    output_path = f"fd://{username}/housing_processed.parquet"
    df.to_parquet(output_path)

    return f"File saved to {output_path}"

JSON

@fused.udf
def udf():
    import pandas as pd
    
    df = pd.DataFrame({'col1': [1, 2], 'col2': [3, 4]})
    
    df.to_json("fd://my-data/output.json")
    
    return "Saved!"

Where to Save Files

Storage	Path Format	Best For
Fused S3 bucket	fd://path/file.parquet	Persistent storage, sharing
Mounted disk	/mnt/cache/file.parquet	Temporary files, caching
Your own S3	s3://bucket/file.parquet	Enterprise integration

See Cloud Storage for details on connecting your own buckets.