Add R package wrapper for PolicyEngine TAXSIM emulator

[PavelMakarchuk]

Summary

Adds an R package (policyenginetaxsim) that allows R users to run the PolicyEngine TAXSIM emulator directly from R.

Closes #690

Changes

• New r-package/policyenginetaxsim/ directory containing the R package
• Uses reticulate to bridge R and Python
• Automatically sets up Python environment (Miniconda) if needed

Functions

Function	Purpose
policyengine_calculate_taxes()	Calculate taxes for tax units
setup_policyengine()	One-time Python environment setup
check_policyengine_setup()	Verify setup is complete
compare_with_taxsim()	Compare with NBER TAXSIM (via usincometaxes)
summary_comparison()	Get comparison statistics

Usage

# Install
devtools::install_github("PolicyEngine/policyengine-taxsim",
                          subdir = "r-package/policyenginetaxsim")

# Setup (one time, ~5-10 min)
library(policyenginetaxsim)
setup_policyengine()

# Calculate taxes
my_data <- read.csv("household_data.csv")
results <- policyengine_calculate_taxes(my_data)

# Compare with TAXSIM
comparison <- compare_with_taxsim(my_data)

Testing

• Verified R package produces identical output to Python emulator
• Tested across 15 diverse scenarios (various income levels, states, filing statuses, income types)
• All 32 output columns match with <$0.01 difference (floating point rounding only)

Test Plan

• Test on fresh Mac without Python
• Test on Windows
• Test on Linux
• Test with large datasets (1000+ records)

🤖 Generated with Claude Code