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Comparison · Infra & APIs
RSA vs volcalc
A side-by-side editorial comparison of RSA and volcalc — release velocity, themes, recent moves, and the top alternatives to consider.
RSA vs volcalc: at a glance
What is RSA?
Four years quiet, then two releases ninety seconds apart, both about drawing better plots
RSA implements response surface analysis for congruence questions in psychology, built on lavaan. After four and a half years of silence the maintainer pushed 0.10.6 and 0.10.8 within ninety seconds of each other on 2 October 2025, so the feed's version sequence is a backfill of accumulated work rather than two separate release events. Both are plotting releases: user-defined lines and points on the surface, stilts for selected data points, and separate control of point fill and border colour.
What is volcalc?
Rebuilt itself around SMILES and .mol input, then made the chemistry configurable
volcalc estimates the volatility of chemical compounds from their structure, implementing the SIMPOL.1 group-contribution method and the Meredith et al. variant. Version 2.0.0 severed the package from KEGG: calc_vol() takes .mol file paths or SMILES strings directly, is vectorized over multiple compounds, and the group-contribution maths was split into its own simpol1() function. Work since has been chemistry accuracy and configurability — the full set of SIMPOL.1 functional groups, volatility thresholds for clean atmosphere, polluted atmosphere or soil, user-supplied temperature, and a validate option returning NA when structure parsing looks suspect.
RSA vs volcalc: editorial side-by-side
RSA
0.0INFRA · APIS
Four years quiet, then two releases ninety seconds apart, both about drawing better plots
◆ Current state
RSA implements response surface analysis for congruence questions in psychology, built on lavaan. After four and a half years of silence the maintainer pushed 0.10.6 and 0.10.8 within ninety seconds of each other on 2 October 2025, so the feed's version sequence is a backfill of accumulated work rather than two separate release events. Both are plotting releases: user-defined lines and points on the surface, stilts for selected data points, and separate control of point fill and border colour.
◆ Where it's heading
The statistical core has been stable since 0.10.0 in 2020, which added control variables, pooled centering and a corrected AICc. Everything since is either plot customisation or a reaction to a dependency — lavaan model comparison, rgl deprecations, tkrplot on Apple Silicon, the ggplot2 fill aesthetic. This is a mature method implementation in maintenance, where the visible work is making its surface plots publishable.
◆ Prediction
Further releases are most likely dependency reactions, with rgl and ggplot2 the two that have repeatedly forced changes, and plot customisation arriving in batches whenever the maintainer returns to the package.
volcalc
0.0INFRA · APIS
Rebuilt itself around SMILES and .mol input, then made the chemistry configurable
◆ Current state
volcalc estimates the volatility of chemical compounds from their structure, implementing the SIMPOL.1 group-contribution method and the Meredith et al. variant. Version 2.0.0 severed the package from KEGG: calc_vol() takes .mol file paths or SMILES strings directly, is vectorized over multiple compounds, and the group-contribution maths was split into its own simpol1() function. Work since has been chemistry accuracy and configurability — the full set of SIMPOL.1 functional groups, volatility thresholds for clean atmosphere, polluted atmosphere or soil, user-supplied temperature, and a validate option returning NA when structure parsing looks suspect.
◆ Where it's heading
The arc runs from a script tied to one database toward a general structure-to-volatility tool. Dropping KEGG from the core in 2.0.0, then removing KEGGREST as a dependency entirely in 2.2.0, took the package from volatility for KEGG compounds to volatility for any structure a user can supply. The accompanying manuscript published in 2023, and the changelog since has been careful about coefficient double-counting — amines and amides have each been corrected — which suggests the group definitions are the part under active scrutiny.
◆ Prediction
The smarts_simpol1 dataset added in 2.2.0 documents how functional groups are defined, pointing toward further estimation methods alongside SIMPOL.1 and Meredith; splitting simpol1() out in 2.0.0 was stated to be groundwork for exactly that.
Alternatives to RSA and volcalc
Other Infra & APIs 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 RSA or volcalc.
Cursor
Cursor's agents stop waiting to be asked - they subscribe, and they hold a goal until it's done.
incident.io
Nexus does the diagnosis; the agent is now reaching into the status page too.
Warp
Warp turned its quarter of software-factory essays into infrastructure you can buy.
Okta
Okta's developer blog is a Cross App Access campaign, now diluted by advocacy-team storytelling.
tealeaves
A leaf-temperature model that finished its job in 2020 and has stayed finished
Recent activity from RSA and volcalc
Latest ship moves from both products, interleaved chronologically. ⚡ = editorial spark.
- 10mo agoRSAUser-defined lines and points on response surface plots
- 10mo agoRSAStilts and separate point fill and border colours in plotRSA
- 1y agovolcalcParsing validation, user-supplied temperature, KEGGREST dropped
- 2y agovolcalcAuthorship and citation updates
- 2y agovolcalcSMILES input, environment-specific thresholds, missing functional groups
- 2y agovolcalcRebuilt around .mol and SMILES input; SIMPOL.1 split into simpol1() ⚡
- 3y agovolcalcAmines group removed to stop double-counting with primary amines
- 3y agovolcalcbug fix: standard temperature
- 5y agoRSADemo dataset for control variables and cubic RSA; SRSQD fix
- 5y agoRSAtkrplot moved to Suggests for Apple Silicon
- 6y agoRSAFixes for R 4.0.0 stringsAsFactors and discrepancy output
- 6y agoRSAControl variables, pooled centering and a corrected AICc
Frequently asked questions
What is the difference between RSA and volcalc?
They serve adjacent needs but don't currently overlap on shipped themes. RSA and volcalc 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 RSA better than volcalc?
Sparkpulse doesn't pick a winner — we score release velocity, not feature parity. RSA and volcalc 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 Infra & APIs products to evaluate alongside.
What are the best alternatives to RSA?
Top RSA alternatives in Infra & APIs are ranked by recent ship velocity. Browse the "RSA alternatives" section above for the current picks, or visit /alternatives/rsa for the full list with editorial commentary on each.
What are the best alternatives to volcalc?
Top volcalc alternatives in Infra & APIs are ranked by recent ship velocity. Browse the "volcalc alternatives" section above for the current picks, or visit /alternatives/volcalc for the full list with editorial commentary on each.