find_cran_date.py - Find CRAN snapshot date for R packages

Description¶

Determines the minimum CRAN snapshot date for a set of pinned R packages. Given a file specifying R package versions (R script, renv.lock, DESCRIPTION, or CSV), this tool queries the crandb API to find when all specified package versions were simultaneously available on CRAN, then reports matching Docker images and Posit Package Manager snapshot URLs.

Usage¶

python tools/find_cran_date.py <input_file> [--output <path>] [--verbose]

Arguments¶

• input_file (required) - File containing R package specifications

  • Supported formats: R script, renv.lock, DESCRIPTION, CSV

• --output - Output file path for saving results (optional)

• --verbose - Enable verbose output (optional)

Examples¶

# Analyze R setup script
python tools/find_cran_date.py 209465/Code/0_setup.R

# Save results to file
python tools/find_cran_date.py renv.lock --output generated/notes-for-r.md

# Verbose mode
python tools/find_cran_date.py packages.csv --verbose

Output¶

The tool reports:

1. Minimum CRAN snapshot date when all package versions existed

2. Matching rocker/verse Docker container image

3. Posit Package Manager snapshot URL for reproducible installations

4. Compatible R version(s)

Requirements¶

• Python >= 3.6

• Standard library only (urllib, json, datetime, argparse)

• Internet connection to query crandb API

Use Cases¶

• Determine the correct CRAN snapshot for reproducible R environments

• Find appropriate rocker/verse Docker images for historical package versions

• Generate Posit Package Manager URLs for package installation

• Verify package availability on specific dates

Technical Details¶

• Queries https://crandb.r-pkg.org for package publication dates

• Caches API responses in ~/.cache/cran-pkg-dates/ to minimize requests

• Supports R versions 4.0.0 through 4.5.3

• Parses multiple input formats automatically

See Also¶

• Pipeline 9-find-cran-date in bitbucket-pipelines.yml

• check_r_deps.R - Find R package dependencies