packages/shared-skills/skills/data-scientist/references/execution-templates.md
Use when:
uv run --with numpy --with duckdb python -c "
import duckdb
# Simple query - direct file access
result = duckdb.sql('''
SELECT
category,
COUNT(*) as count,
AVG(amount) as avg_amount,
SUM(amount) as total
FROM 'data.csv'
WHERE date >= '2024-01-01'
GROUP BY category
ORDER BY total DESC
LIMIT 10
''').pl()
print('**Results**')
print(result)
print(f'\\nProcessed {len(result)} categories')
"
Use when:
uv run --with numpy --with polars python -c "
import polars as pl
# Lazy evaluation for optimal performance
result = (
pl.scan_csv('data.csv') # Lazy scan
.filter(
(pl.col('amount') > 1000) &
(pl.col('status') == 'active') &
(pl.col('date') >= '2024-01-01')
)
.sort('amount', descending=True)
.head(100)
.collect() # Execute optimized plan
)
print('**Filtered and Sorted Results**')
print(result)
print(f'\\nFound {len(result)} matching rows')
"
Use when:
uv run --with numpy --with duckdb --with polars --with pyarrow python -c "
import duckdb
import polars as pl
print('Phase 1: DuckDB for complex join (3x faster)')
# DuckDB excels at joins
joined = duckdb.sql('''
SELECT
o.order_id,
o.amount,
c.customer_id,
c.region,
p.category
FROM 'orders.csv' o
JOIN 'customers.csv' c ON o.customer_id = c.customer_id
JOIN 'products.csv' p ON o.product_id = p.product_id
WHERE o.date >= '2024-01-01'
''').pl() # Convert to Polars
print(f'Joined {len(joined):,} rows')
print('\\nPhase 2: Polars for ultra-fast filtering (128x faster)')
# Polars excels at filtering
filtered = (
joined
.filter(
(pl.col('amount') > 100) &
(pl.col('region').is_in(['North', 'South', 'East']))
)
.with_columns([
(pl.col('amount') * 1.1).alias('amount_with_tax')
])
)
print(f'Filtered to {len(filtered):,} rows')
print('\\nPhase 3: DuckDB for final aggregation (4x faster)')
# Back to DuckDB for aggregation
duckdb.register('filtered_data', filtered)
final = duckdb.sql('''
SELECT
region,
category,
COUNT(DISTINCT customer_id) as customers,
SUM(amount_with_tax) as total_revenue,
AVG(amount_with_tax) as avg_transaction
FROM filtered_data
GROUP BY region, category
HAVING total_revenue > 10000
ORDER BY total_revenue DESC
''').pl()
print('\\n**Final Results**')
print(final)
"
Use when:
uv run --with numpy --with polars python -c "
import polars as pl
# Streaming mode - processes data in chunks
result = (
pl.scan_csv('huge_file.csv')
.filter(pl.col('status') == 'active')
.with_columns([
(pl.col('amount') * 1.1).alias('adjusted_amount')
])
.groupby('category')
.agg([
pl.sum('adjusted_amount').alias('total'),
pl.count().alias('count')
])
.collect(streaming=True) # Streaming mode for large data
)
print('**Streaming Results**')
print(result)
print(f'\\nProcessed {result[\"count\"].sum():,} total rows')
"
Use when:
uv run --with numpy --with duckdb --with polars --with pyarrow --with matplotlib python -c "
import duckdb
import matplotlib.pyplot as plt
# Query data
result = duckdb.sql('''
SELECT
date,
SUM(amount) as total
FROM 'data.csv'
GROUP BY date
ORDER BY date
''').pl()
# Create visualization
plt.figure(figsize=(10, 6))
plt.plot(result['date'], result['total'])
plt.xlabel('Date')
plt.ylabel('Total Amount')
plt.title('Daily Total Trends')
plt.xticks(rotation=45)
plt.tight_layout()
plt.savefig('output.png')
print('Chart saved to output.png')
"