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Comparison · Analytics
CMAQ vs collapse
A side-by-side editorial comparison of CMAQ and collapse — release velocity, themes, recent moves, and the top alternatives to consider.
CMAQ vs collapse: at a glance
What is CMAQ?
CMAQ went global in v5.5, and has been patching that surface ever since.
CMAQ is the EPA's Community Multiscale Air Quality modeling system, used for regulatory and research air quality simulation. Its release rhythm is strictly two-tier: numbered major versions carry new science and fresh benchmark datasets, while the x.y.z.n updates carry bug fixes against documentation and benchmarks that stay pinned to the parent version. The current line is v5.5, which introduced CRACMM2 chemistry and coupling to MPAS-A meteorology, followed by three patch rollups.
What is collapse?
collapse got a JSS paper and a 7x fmean speedup in the same release.
collapse provides fast grouped statistical computing and data transformation for R, built on a C backend with its own grouping, hashing and aggregation primitives. The 2.1.x line is a maintenance and optimization series: SIMD multiple-accumulator work delivering roughly 2x on fsum() and 7x on fmean() for systems without OpenMP, a custom internal unlist() with better attribute preservation, and a steady stream of correctness fixes in collap(), pivot() and roworderv().
CMAQ vs collapse: editorial side-by-side
CMAQ
0.0ANALYTICS
CMAQ went global in v5.5, and has been patching that surface ever since.
◆ Current state
CMAQ is the EPA's Community Multiscale Air Quality modeling system, used for regulatory and research air quality simulation. Its release rhythm is strictly two-tier: numbered major versions carry new science and fresh benchmark datasets, while the x.y.z.n updates carry bug fixes against documentation and benchmarks that stay pinned to the parent version. The current line is v5.5, which introduced CRACMM2 chemistry and coupling to MPAS-A meteorology, followed by three patch rollups.
◆ Where it's heading
The v5.5 patches cluster around the newest and most sensitive components. ISAM source apportionment and DDM-3D sensitivity analysis account for corrections in every one of the three updates, and CRACMM2 needed fixes within months of release. That is the expected shape after a major version lands: the science is stable, the instrumentation built on top of it is not. Parallel I/O work in the latest patch suggests the global configurations are now being run at scales that expose throughput limits.
◆ Prediction
The next major version will fold these fixes in with new science, documentation and benchmark data — the release notes state this explicitly each time. Until then, expect further ISAM and DDM-3D corrections, which have appeared in every patch so far.
collapse
0.0ANALYTICS
collapse got a JSS paper and a 7x fmean speedup in the same release.
◆ Current state
collapse provides fast grouped statistical computing and data transformation for R, built on a C backend with its own grouping, hashing and aggregation primitives. The 2.1.x line is a maintenance and optimization series: SIMD multiple-accumulator work delivering roughly 2x on fsum() and 7x on fmean() for systems without OpenMP, a custom internal unlist() with better attribute preservation, and a steady stream of correctness fixes in collap(), pivot() and roworderv().
◆ Where it's heading
The package is consolidating institutionally as much as technically. The repository moved to the fastverse organization with multiple people granted access, the Journal of Statistical Software paper landed as the primary citation, and documentation now includes an AI-generated interactive layer. Technically the focus is the hashing and grouping core — the decision to treat -0 and 0 as equal across funique(), group(), fmatch(), fmode() and their derivatives was made in sync with an equivalent change in Rcpp, and accepted a measured 3% cost to get it. The last release with breaking changes sits outside this six-entry window.
◆ Prediction
Expect further targeted performance work on the grouped statistical functions and continued small correctness fixes; the governance move to fastverse suggests contribution volume rather than direction is what the maintainer is managing.
Alternatives to CMAQ and collapse
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 CMAQ or collapse.
geodist
geodist stays dependency-free and fast, and warns you when 'cheap' distances stop being honest.
errors
errors keeps making uncertainty print the way each scientific field expects.
enpls
enpls has not changed its statistics since 2016 — only its website, twice.
grex
grex is a lookup table with a version number — it ships when the annotation moves.
protr
protr's feature set is finished; the work now is surviving Bioconductor's churn.
See all CMAQ alternatives → · See all collapse alternatives →
Recent activity from CMAQ and collapse
Latest ship moves from both products, interleaved chronologically. ⚡ = editorial spark.
- 2mo agocollapseSIMD accumulators give fmean a 7x speedup without OpenMP
- 7mo agocollapseNegative zero now hashes equal to zero across the package
- 8mo agocollapsecollap() no longer double-aggregates external weights
- 9mo agocollapseCustom unlist() preserves attributes
- 0y agocollapseAssorted bug fixes
- 1y agoCMAQCMAQ 5.5.0.3 enables parallel I/O, fixes DDM-3D control files
- 1y agocollapsena_insert gains by-reference mode; gsplit and pivot speed up
- 1y agoCMAQCMAQ 5.5.0.2 corrects ISAM aerosol and cloud processing
- 1y agoCMAQCMAQ 5.5.0.1 fixes SAPRC mechanism runs and NLCD mapping
- 1y agoCMAQCMAQ 5.5 adds global simulation coupled to MPAS-A ⚡
- 1y agoCMAQCMAQ 5.4.0.5: minor ELMO output fixes
- 2y agoCMAQCMAQ 5.4.0.4 fixes RBSTATS under ROS3, corrects a molecular weight
Frequently asked questions
What is the difference between CMAQ and collapse?
They serve adjacent needs but don't currently overlap on shipped themes. CMAQ and collapse are shipping at a similar cadence (velocity 0.0 vs 0.0, both within Sparkpulse's "active" band). See the at-a-glance table above for a side-by-side breakdown of velocity, recent sparks, and editorial themes.
Is CMAQ better than collapse?
Sparkpulse doesn't pick a winner — we score release velocity, not feature parity. CMAQ and collapse are shipping at a similar cadence (velocity 0.0 vs 0.0, both within Sparkpulse's "active" band). For your specific use case, the alternatives sections above list other Analytics products to evaluate alongside.
What are the best alternatives to CMAQ?
Top CMAQ alternatives in Analytics are ranked by recent ship velocity. Browse the "CMAQ alternatives" section above for the current picks, or visit /alternatives/cmaq for the full list with editorial commentary on each.
What are the best alternatives to collapse?
Top collapse alternatives in Analytics are ranked by recent ship velocity. Browse the "collapse alternatives" section above for the current picks, or visit /alternatives/collapse-r for the full list with editorial commentary on each.