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tissot 0.2.0

Major refactor — modernized engine, new API, and rich plotting.

Breaking changes

• Projection engine switched from reproj to gdalraster::transform_xy(). All projection work is now a single batched GDAL call.

• API renamed: proj.in/proj.out → source/target, following reproj conventions. target is the second positional argument (required); source defaults to "EPSG:4326".

• tissot() input is now any “xy-ish” object (matrix, data.frame, list, length-2 vector) via the internal as_xy() helper. The old lambda/phi positional arguments are replaced by x.

• tissot() returns a tissot_tbl (subclassed tibble) with source and target stored as attributes. Column names changed to: x, y, dx_dlam, dy_dlam, dx_dphi, dy_dphi, scale_h, scale_k, scale_omega, scale_a, scale_b, scale_area, angle_deformation, convergence.

• indicatrix() returns an indicatrix_list (replaces indicatrixes class). Accepts tissot_tbl or raw coordinates + explicit target.

• Removed: indicatrix0(), tissot0(), .prj(), and the internal numericDeriv path. The Jacobian is now computed directly via finite differences.

New features

• plot.indicatrix() and plot.indicatrix_list() with:

  • Reference unit circle overlay (show.circle)
  • Lambda/phi direction axes (show.axes)
  • show.circle and show.axes accept TRUE, FALSE, or a named list of graphical parameters for full customization
  • Colour-coded fill via fill.by (e.g. "scale_area", "angle_deformation")

• print() and summary() methods for tissot_tbl.

• print(), length(), and [ methods for indicatrix_list.

• tissot_map() and tissot_abline() accept explicit target argument.

• as_xy() internal helper coerces diverse coordinate inputs.

• resolve_gpar() internal helper for the logical-or-list graphical parameter pattern.

Internal

• Fully vectorized Jacobian computation — no per-point loop.
• Computation uses 3N batched transform_xy() call.
• Test suite added (testthat).

These binaries (installable software) and packages are in development.
They may not be fully stable and should be used with caution. We make no claims about them.
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