• Add internal workaround for udunits2 bug with parsing of units that contain
  "per", e.g. "percent" or "person"; #414

• Update minimum Rcpp version; #421

• Fix print methods for units and mixed_units, which now correctly return
  invisibly the object being printed; #422

• Wrap all pointers to avoid memory leaks derived from errors.

• Check for exception propagation in udunits2; #423

• Fix ud_convert() for empty input vectors; #428

• Breaking change: a new tokenizer fixes longstanding issues with parsing
  complex unit expressions, but may break existing code that relied on the
  previous (buggy) behavior. The major change is that now numbers are
  consistently treated as prefixes, so that units like ml / min / 1.73m^2
  used in physiology are now correctly parsed as ml / (min * 1.73 * m^2).
  See ?as_units for details; #416 addressing #221, #383

• Printing: follow NIST recommendations. In particular, numerator and
  denominator are separated by a single slash, and a parenthesis is used when
  the denominator contains several symbols (see example above); #86

• Vectorize ud_*() helpers; #405 addressing #404

• Loading units no longer initializes the RNG state; #409

• Fix scale training in ggplot2 scales; #412

• Add scale_{type}_units() scales for additional continuous aesthetics
  (colour, fill, alpha, size, linewidth); #369

• Implement matrixOps.units, with support for %*% (R >= 4.3.0); #226

• New convert_to_base() implements conversion to base units; #132 @jamarav

Contributors

• @jamarav

• Deep copy of ud_convert() input to avoid side effects; #403

• Set C++17 standard for old versions of R; #402

• Add methods for cbind and rbind; fixes #311

• Performance improvements in data.frame methods; suggested in #361 @grcatlin

• Fix weighted.mean.units for unitless objects; #363

• Fix incorrect use of round() in %% and %/% methods; #365 @UchidaMizuki

• Fix ggplot2 deprecation warnings; #367

• Fix hist() error; #368

• Add support for lims() in ggplot2 scales; #370

• Fix simplification of inverse units; #378

• Replace call to Rf_error() with Rcpp::stop(); RcppCore/Rcpp#1247

• Fix UBs in the C++ glue code; #380

• Add support for brew path discovery in macOS; #384

• Several performance improvements; #387, #388, #393, #400 addressing #386, #389

• Improve keep_units() helper for more general usage scenarios;
  #394 @d-morrison addressing #392

• Add ud_convert() to convert units of a vector; #399 @dlebauer addressing #398

• Fix scale_units for upcoming version of ggplot2; #401

Contributors

• @dlebauer
• @d-morrison
• @UchidaMizuki
• @grcatlin

• avoid -Wformat-security warning on CRAN

• Identical unit division and multiplication will now respect
  units_options(simplify = FALSE) reverting a change from #310; #355
  @billdenney

• Fix scale_units when both unit and trans are specified; #357

Contributors

• @billdenney

• Remove tolerance from comparisons with logical operators, restoring behavior changed in previous release; #353 addressing #351

• Names are preserved when doing unit conversions; #305 @billdenney

• Identical units will always divide (/) and allow integer division (%/%).
  And, inverse units will always be able to multiply; #310 @billdenney

• Compare units via ud_compare(), fixing inconsistent results for aliases
  and symbols; #339, #346, #347

• Fix units<-() to treat an empty unit the same as NULL; #332

• New as.data.frame() method for mixed_units; #309

• Use short paths for database loading on Windows to fix UTF-16 issues; #342

• Add example in the docs about reversing a ggplot2 units scale; #343

• Force storage mode to double; #344 addressing #324

• Fix units in transformed axis; #323

• Consider unitless as radians in trigonometric functions; #328

Contributors

• @billdenney

• fix %/% and %% if arguments have different units; #313

• fix multiplier parsing for exp(log(x)) operations; #321

• fix specification of secondary axes with scale_units; #326

• enhance unit mapping for newly installed units; #290

• remove deprecations: install_symbolic_unit, remove_symbolic_unit,
  install_conversion_constant, install_conversion_offset; #290

• fix multipliers for round trip log-exp operations; #292

• integrate ggplot2 scales (previously in the ggforce package) to
  automatically print axes with units; #294 addressing #164

• fix all.equal.units for non-units current

• fix zero power; #285

• fix unique.units to support arrays and matrices, implement methods for
  duplicated and anyDuplicated

• fix plot labels with spaces; #298 addressing #297

• always add units to labels, including user-provided ones; as part of #298

• new symbols/names with a percentage character are not allowed due to an
  upstream bug; #289