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hardhat vs loo

A side-by-side editorial comparison of hardhat and loo — release velocity, themes, recent moves, and the top alternatives to consider.

Shared themes:r-stats

hardhat vs loo: at a glance

Featurehardhatloo
SectorAnalyticsAnalytics
Velocity score0.02.5
Sparks · 30d00
Top themestidymodels, r-stats, machine-learning, infrastructurebayesian, cross-validation, stan, r-stats
Last editorial update1h ago1h ago
WebsiteVisit →Visit →

What is hardhat?

hardhat keeps adding the contracts tidymodels needs next

hardhat is the infrastructure layer under tidymodels, defining the preprocessing and extraction contracts other packages implement. Its releases read as a list of new generics and vector classes: extract_postprocessor(), extract_fit_time(), extract_tailor(), and a quantile_pred() class for quantile-regression output. The newest release is narrow warning and missing-value handling in mold().

Read the full hardhat trajectory →

What is loo?

loo keeps rewriting the diagnostics Bayesian modellers read off model comparison

loo computes leave-one-out cross-validation and model comparison for Bayesian models in the Stan ecosystem. Two releases in this window changed what users actually read: 2.7.0 replaced the fixed Pareto-k thresholds with sample-size-dependent ones and dropped the middle category, and 2.10.0 reshaped loo_compare's output into a data.frame with new uncertainty columns. The releases between are diagnostic robustness fixes and moment-matching corrections.

Read the full loo trajectory →

hardhat vs loo: editorial side-by-side

H
hardhat
ANALYTICS
0.0

hardhat keeps adding the contracts tidymodels needs next

◆ Current state

hardhat is the infrastructure layer under tidymodels, defining the preprocessing and extraction contracts other packages implement. Its releases read as a list of new generics and vector classes: extract_postprocessor(), extract_fit_time(), extract_tailor(), and a quantile_pred() class for quantile-regression output. The newest release is narrow warning and missing-value handling in mold().

◆ Where it's heading

Each addition here lands ahead of a user-facing feature elsewhere in tidymodels — the postprocessor and tailor generics precede the postprocessing workflow, quantile_pred() precedes quantile prediction in parsnip. The package's own surface stays deliberately small and its cadence follows what the rest of the stack is about to need.

◆ Prediction

Expect further extraction generics and prediction-type classes as tidymodels builds out postprocessing, with hardhat's own API remaining thin.

L
loo
ANALYTICS
2.5

loo keeps rewriting the diagnostics Bayesian modellers read off model comparison

◆ Current state

loo computes leave-one-out cross-validation and model comparison for Bayesian models in the Stan ecosystem. Two releases in this window changed what users actually read: 2.7.0 replaced the fixed Pareto-k thresholds with sample-size-dependent ones and dropped the middle category, and 2.10.0 reshaped loo_compare's output into a data.frame with new uncertainty columns. The releases between are diagnostic robustness fixes and moment-matching corrections.

◆ Where it's heading

The package is being brought in line with the current PSIS literature rather than extended with new features, and the practical effect is that the numbers practitioners quote in papers keep changing meaning. Work is increasingly delegated to posterior for shared computations, and the project has added contributor process, benchmarks and a published AI contribution policy.

◆ Prediction

Expect further work on comparison diagnostics — the p_worse and diag_* columns are new enough that their defaults and documentation will likely be revised next.

Alternatives to hardhat and loo

Other Analytics products tracked by Sparkpulse, ranked by recent ship velocity. Each card links to a full editorial trajectory and lets you pivot into a head-to-head comparison with either hardhat or loo.

See all hardhat alternatives → · See all loo alternatives →

Recent activity from hardhat and loo

Latest ship moves from both products, interleaved chronologically. ⚡ = editorial spark.

  1. 20d agoloopsis_smooth_tail revert and simplify arg restored
  2. 1mo agolooloo_compare returns a data.frame with new uncertainty columns
  3. 4mo agohardhatmold() warning and quantile missing-value fixes
  4. 7mo agolooStacking overflow fixes and posterior-based ESS
  5. 11mo agohardhatextract_tailor() generic added
  6. 1y agohardhatquantile_pred() class for quantile regression output
  7. 2y agohardhatextract_postprocessor() and extract_fit_time() generics
  8. 2y agolooMore robust Pareto-k diagnostics and moment matching
  9. 2y agolooPareto-k thresholds now depend on sample size
  10. 2y agohardhatDocumentation topic renamed at CRAN's request
  11. 3y agolooLOO predictive metrics and CRPS scoring functions
  12. 3y agohardhatMulti-outcome prediction helpers and one-hot factor encoding

Frequently asked questions

What is the difference between hardhat and loo?

Both compete on the same themes — r-stats — within Analytics. loo is currently shipping more aggressively (velocity 2.5 vs 0.0), with 0 editorial sparks in the last 30 days against 0. See the at-a-glance table above for a side-by-side breakdown of velocity, recent sparks, and editorial themes.

Is hardhat better than loo?

Sparkpulse doesn't pick a winner — we score release velocity, not feature parity. loo is currently shipping more aggressively (velocity 2.5 vs 0.0), with 0 editorial sparks in the last 30 days against 0. For your specific use case, the alternatives sections above list other Analytics products to evaluate alongside.

What are the best alternatives to hardhat?

Top hardhat alternatives in Analytics are ranked by recent ship velocity. Browse the "hardhat alternatives" section above for the current picks, or visit /alternatives/hardhat for the full list with editorial commentary on each.

What are the best alternatives to loo?

Top loo alternatives in Analytics are ranked by recent ship velocity. Browse the "loo alternatives" section above for the current picks, or visit /alternatives/loo for the full list with editorial commentary on each.