princurve 2.1.6

• BUG FIX project_to_curve(): Return error message when x or s contain
  insufficient rows.

• BUG FIX unit tests: Switch from svg() to pdf() as support for svg()
  might be optional.

princurve 2.1.5

• BUG FIX project_to_curve(): Fix pass-by-reference bug, issue #33. Thanks
  to @szcf-weiya for detecting and fixing this bug!

princurve 2.1.4

• Fix warning in stats::approx() due to changes made in R 3.6.

• Defuncted principal.curve() and get.lam().

princurve 2.1.3

• Removed extra dependencies in princurve by removing vignettes; fixes #28.

• Fully deprecated principal.curve() and get.lam().

princurve 2.1.2

• DOCUMENTATION: Use the magick package to generate animated GIFs in
  the vignette, instead of the animation package, because
  animation uses ffmpeg which is not installed on all CRAN systems.

• DEPRECATION: Added deprecation which will be triggered starting from 2018-08-01
  upon calling principal.curve() or get.lam().

princurve 2.1.1

• DOCUMENTATION: Added vignettes on the algorithm behind princurve and
  on benchmarking results between princurve 1.1 and 2.1.

• BUG FIX principal_curve(): Don't apply rownames to curve as approx_points could
  be set to a different value other than nrow(x).

• TESTING: Skip comparison unit test between princurve 1.1 and 2.1 on CRAN.

• MINOR CHANGE project_to_curve(): Attempt to fix rchk warnings by not using
  x(i, j) = v notation but instead x[j * x.nrow() + i] = v.

• DOCUMENTATION: Fix in README documentation.

princurve 2.1.0

• BUG FIX principal_curve(): avoid division by zero when the initial principal curve
  has already converged.

• BUG FIX project_to_curve(): set dimension names of outputted s correctly.

• DOCUMENTATION: Added cran-comments.md and revdep to repository.

• MINOR CHANGE: Removed adjust_range(); use grDevices::extendrange() instead.

• TESTING start_circle(): Added unit tests.

• BUG FIX start_circle(): Make sure circle is centered and scaled correctly.

• MINOR CHANGE: Move smoother functions from inside principal_curve() to
  a list smoother_functions.

• TESTING smoother_functions: Added tests to ensure each of the smoother
  functions work correctly.

• SPEED UP project_to_curve(): Significantly speed up this function by not
  allocation objects that don't need allocation, and pre-allocating objects
  that do.

• SPEED UP principal_curve(): Added approx_points parameter. This allows
  approximation of the curve between smoothing and projection, to ensure
  principal_curve() scales well to higher numbers of samples.

princurve 2.0.4

• BUG FIX: Fixed issues with legacy principal.curve() and get.lam() (#8).
• TESTING: Perform direct comparison between the current princurve and
  princurve 1.1-12 to check whether principal.curve() and get.lam() produce
  output with exactly the same format and almost exactly the same values.
• SIGNIFICANT CHANGE: Remove the ord parameter from project_to_curve(),
  in order to reduce the amount of Rcpp code a little bit.
• DOCUMENTATION: Improved citations (#10).
• DOCUMENTATION: Improved news (#11).
• SPEED UP project_to_curve: Do not compute lambda accurately as it
  is only used to order the points in x.
• MINOR CHANGE: Added ... argument to whiskers().
• DOCUMENTATION: Minor fix in output documentation of principal_curve().
• DOCUMENTATION: Added more information to the README.

princurve 2.0.3

• SIGNIFICANT CHANGES: Reimplemented project_to_curve() completely in
  Rcpp, thereby completely removing all Fortran code from princurve.
• TESTING: test both on linux and osx.
• TESTING: Added tests to ensure project_to_curve() works similar to
  legacy get.lam().