Nail

nail Plugin

Lightning-fast data analysis CLI for Parquet, CSV, and XLSX files. Describe, filter, transform, join, compare, and analyze datasets with rich statistics and schema introspection.

Commands

Data Analysis

• nail data describe — Show global file overview and metadata
• nail data stats — Calculate descriptive statistics
• nail data head — Display first N rows
• nail data schema — Display schema information
• nail data convert — Convert between file formats

Utility

• nail self version — Print nail version
• nail _ _ — Passthrough to nail CLI

Usage Examples

• "Describe this Parquet file"
• "Show the first 20 rows of the dataset"
• "Calculate statistics for the price and volume columns"
• "Convert this CSV to Parquet"
• "Show the schema of the data file"

Installation

cargo install nail-parquet

Examples

# Describe a dataset
nail data describe sales.parquet

# Statistics for specific columns
nail data stats sales.parquet -c "revenue,profit" --percentiles "0.5,0.9,0.99"

# Correlation matrix
nail _ _ correlations sales.parquet -c "price,volume,discount" --tests t_test

# Frequency distribution
nail _ _ frequency sales.parquet -c "category,region"

# First 20 rows
nail data head sales.parquet -n 20

# Display schema
nail data schema sales.parquet

# Convert CSV to Parquet
nail data convert data.csv -o data.parquet

# Convert Parquet to JSON
nail data convert data.parquet -o data.json -f json

# Remove duplicates
nail _ _ dedup raw.parquet --row-wise -c "id" -o unique.parquet

# Detect and remove outliers
nail _ _ outliers unique.parquet -c "price" --method iqr --remove -o cleaned.parquet

# Create a new column
nail _ _ create cleaned.parquet --column "margin=(price-cost)/price" -o enriched.parquet

# Bin continuous variables
nail _ _ binning opt.parquet -c "age" -b "18,25,35,50,65" --method custom --labels "18-24,25-34,35-49,50-64,65+" -o binned.parquet

# Pivot table
nail _ _ pivot binned.parquet -i "age_binned" -c "category" -l "revenue" --agg sum -o summary.parquet

# Compare two datasets
nail _ _ diff yesterday.parquet --compare today.parquet --keys "id" --changes-only

Key Features

• Multi-format support: Parquet, CSV, XLSX, JSON, and text output
• Rich statistics: Descriptive stats, correlations, frequency distributions, outliers
• Data transformation: dedup, filter, binning, pivot, merge, split, sort, shuffle
• Schema introspection: Display column types, metadata, and schema details
• Format conversion: Convert between Parquet, CSV, XLSX, JSON, and text
• Column operations: Create, rename, drop, select, fill missing values
• Row operations: head, tail, sample, preview, filter, deduplicate
• Join datasets: merge two datasets on common keys
• Compare datasets: diff with key-based change detection
• Performance: Multi-threaded with -j jobs flag
• Output control: -o for output file, -f for format override

Notes

• Use nail <command> --help for full usage details of any subcommand
• The -f flag overrides output format: json, csv, parquet, or text
• The -j flag controls parallelism (useful for large datasets)
• Many commands support -o to write results to a file instead of stdout
• nail auto-detects input format from file extension