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ray-data

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by firecrawl · part of firecrawl/ai-research-skills

Scalable data processing for ML workloads. Streaming execution across CPU/GPU, supports Parquet/CSV/JSON/images. Integrates with Ray Train, PyTorch,…

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🧩 One of 7 skills in the firecrawl/ai-research-skills package — works on its own, and pairs well with its siblings.

Scalable data processing for ML workloads. Streaming execution across CPU/GPU, supports Parquet/CSV/JSON/images. Integrates with Ray Train, PyTorch,…

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by firecrawl

Scalable data processing for ML workloads. Streaming execution across CPU/GPU, supports Parquet/CSV/JSON/images. Integrates with Ray Train, PyTorch,… npx skills add https://github.com/firecrawl/ai-research-skills --skill ray-data Download ZIPGitHub11

Ray Data - Scalable ML Data Processing

Distributed data processing library for ML and AI workloads.

When to use Ray Data

Use Ray Data when:

  • Processing large datasets (>100GB) for ML training

  • Need distributed data preprocessing across cluster

  • Building batch inference pipelines

  • Loading multi-modal data (images, audio, video)

  • Scaling data processing from laptop to cluster

Key features:

  • Streaming execution: Process data larger than memory

  • GPU support: Accelerate transforms with GPUs

  • Framework integration: PyTorch, TensorFlow, HuggingFace

  • Multi-modal: Images, Parquet, CSV, JSON, audio, video

Use alternatives instead:

  • Pandas: Small data (<1GB) on single machine

  • Dask: Tabular data, SQL-like operations

  • Spark: Enterprise ETL, SQL queries

Reading data

From cloud storage

Copy & paste — that's it
import ray

# Parquet (recommended for ML)
ds = ray.data.read_parquet("s3://bucket/data/*.parquet")

# CSV
ds = ray.data.read_csv("s3://bucket/data/*.csv")

# JSON
ds = ray.data.read_json("gs://bucket/data/*.json")

# Images
ds = ray.data.read_images("s3://bucket/images/")

From Python objects

Copy & paste — that's it
# From list
ds = ray.data.from_items([{"id": i, "value": i * 2} for i in range(1000)])

# From range
ds = ray.data.range(1000000) # Synthetic data

# From pandas
import pandas as pd
df = pd.DataFrame({"col1": [1, 2, 3], "col2": [4, 5, 6]})
ds = ray.data.from_pandas(df)

Transformations

Map batches (vectorized)

Copy & paste — that's it
# Batch transformation (fast)
def process_batch(batch):
 batch["doubled"] = batch["value"] * 2
 return batch

ds = ds.map_batches(process_batch, batch_size=1000)

Row transformations

Copy & paste — that's it
# Row-by-row (slower)
def process_row(row):
 row["squared"] = row["value"] ** 2
 return row

ds = ds.map(process_row)

Filter

Copy & paste — that's it
# Filter rows
ds = ds.filter(lambda row: row["value"] > 100)

Group by and aggregate

Copy & paste — that's it
# Group by column
ds = ds.groupby("category").count()

# Custom aggregation
ds = ds.groupby("category").map_groups(lambda group: {"sum": group["value"].sum()})

GPU-accelerated transforms

Copy & paste — that's it
# Use GPU for preprocessing
def preprocess_images_gpu(batch):
 import torch
 images = torch.tensor(batch["image"]).cuda()
 # GPU preprocessing
 processed = images * 255
 return {"processed": processed.cpu().numpy()}

ds = ds.map_batches(
 preprocess_images_gpu,
 batch_size=64,
 num_gpus=1 # Request GPU
)

Writing data

Copy & paste — that's it
# Write to Parquet
ds.write_parquet("s3://bucket/output/")

# Write to CSV
ds.write_csv("output/")

# Write to JSON
ds.write_json("output/")

Performance optimization

Repartition

Copy & paste — that's it
# Control parallelism
ds = ds.repartition(100) # 100 blocks for 100-core cluster

Batch size tuning

Copy & paste — that's it
# Larger batches = faster vectorized ops
ds.map_batches(process_fn, batch_size=10000) # vs batch_size=100

Streaming execution

Copy & paste — that's it
# Process data larger than memory
ds = ray.data.read_parquet("s3://huge-dataset/")
for batch in ds.iter_batches(batch_size=1000):
 process(batch) # Streamed, not loaded to memory

Common patterns

Batch inference

Copy & paste — that's it
import ray

# Load model
def load_model():
 # Load once per worker
 return MyModel()

# Inference function
class BatchInference:
 def __init__(self):
 self.model = load_model()

 def __call__(self, batch):
 predictions = self.model(batch["input"])
 return {"prediction": predictions}

# Run distributed inference
ds = ray.data.read_parquet("s3://data/")
predictions = ds.map_batches(BatchInference, batch_size=32, num_gpus=1)
predictions.write_parquet("s3://output/")

Data preprocessing pipeline

Copy & paste — that's it
# Multi-step pipeline
ds = (
 ray.data.read_parquet("s3://raw/")
 .map_batches(clean_data)
 .map_batches(tokenize)
 .map_batches(augment)
 .write_parquet("s3://processed/")
)

Integration with ML frameworks

PyTorch

Copy & paste — that's it
# Convert to PyTorch
torch_ds = ds.to_torch(label_column="label", batch_size=32)

for batch in torch_ds:
 # batch is dict with tensors
 inputs, labels = batch["features"], batch["label"]

TensorFlow

Copy & paste — that's it
# Convert to TensorFlow
tf_ds = ds.to_tf(feature_columns=["image"], label_column="label", batch_size=32)

for features, labels in tf_ds:
 # Train model
 pass

Supported data formats

Format Read Write Use Case Parquet ✅ ✅ ML data (recommended) CSV ✅ ✅ Tabular data JSON ✅ ✅ Semi-structured Images ✅ ❌ Computer vision NumPy ✅ ✅ Arrays Pandas ✅ ❌ DataFrames

Performance benchmarks

Scaling (processing 100GB data):

  • 1 node (16 cores): ~30 minutes

  • 4 nodes (64 cores): ~8 minutes

  • 16 nodes (256 cores): ~2 minutes

GPU acceleration (image preprocessing):

  • CPU only: 1,000 images/sec

  • 1 GPU: 5,000 images/sec

  • 4 GPUs: 18,000 images/sec

Use cases

Production deployments:

  • Pinterest: Last-mile data processing for model training

  • ByteDance: Scaling offline inference with multi-modal LLMs

  • Spotify: ML platform for batch inference

References

Resources