Migrate frame settings to the new Frame/Axis syntax across examples and docs

[seisman]

PyGMT now supports the newer Frame/Axis syntax for frame settings (#4406), although it is still not feature-complete. However, many examples and documentation pages continue to use the legacy string- or list-based frame arguments. It would be beneficial to migrate these usages so that the codebase consistently demonstrates and promotes the newer syntax.

I'm still debating whether to continue supporting string-style frame settings (e.g., frame="WSen", frame="afg"), considering that they're simple and widely used. However, at a minimum, list-style frame settings should be migrated to the Frame/Axis classes.

For example:

• frame=["xa10", "ya5", "+tTitle"] => frame=Frame(xaxis=Axis(annot=10), yaxis=Axis(annot=5), title="Title")

To locate remaining usages of string- or list-based frame settings, you can use:

• grep -R 'frame="' **/*.py
• grep -R 'frame=\[' **/*.py

Contributions are welcome! A good way to help would be to:

1. Identify files or cases that still use string or list-based frame arguments
2. Update them to use Frame/Axis where appropriate
3. Verify that the updated examples render correctly
4. Submit small, focused PRs

Below is a list of files that still use the list-based frame settings:

• examples/gallery/3d_plots/3d_bar.py
  DOC/Gallery example "3-D bar plot": Migrate frame settings to the new Frame/Axis syntax #4496
• examples/gallery/3d_plots/grdview_surface.py
  DOC/Gallery example "Plotting a surface": Migrate frame settings to the new Frame/Axis syntax #4497
  DOC/Gallery example "Plotting a surface": Migrate frame settings to the new Frame/Axis syntax; part 2 #4504
  Frame: Allow setting 'axis' and 'zaxis' simultaneously #4498
• examples/gallery/3d_plots/scatter3d.py
  DOC/Gallery example "3-D scatter plots": Migrate frame settings to the new Frame/Axis syntax #4502
• examples/gallery/basemaps/double_y_axes.py
  DOC/Gallery example "Double Y-axes graph": Migrate frame settings to the new Frame/Axis syntax #4503
• examples/gallery/basemaps/ternary.py
  POC: DOC/Gallery example "Ternary diagram": Migrate frame settings to the new Frame/Axis syntax #4505
• examples/gallery/embellishments/colorbar.py
  DOC/Gallery example "Colorbars": Migrate frame settings to the new Frame/Axis syntax #4506
• examples/gallery/embellishments/colorbars_multiple.py
  DOC/Gallery example "Multiple colormaps": Migrate frame settings to the new Frame/Axis syntax #4507
• examples/gallery/embellishments/inset.py
  DOC/Gallery example "Inset": Migrate frame settings to the new Frame/Axis syntax #4508
• examples/gallery/embellishments/inset_rectangle_region.py
  DOC/Gallery example "Inset map showing a rectangular region": Migrate frame settings to the new Frame/Axis syntax #4511
• examples/gallery/embellishments/legend.py
  DOC/Gallery example "Legend": Migrate frame settings to the new Frame/Axis syntax #4512
• examples/gallery/embellishments/scalebar.py
  DOC/Gallery example "Scale bar": Migrate frame settings to the new Frame/Axis syntax #4513
• examples/gallery/histograms/blockm.py
  DOC/Gallery example "Blockmean": Migrate frame settings to the new Frame/Axis syntax #4514
• examples/gallery/histograms/histogram.py
  DOC/Gallery example "Histogram": Migrate frame settings to the new Frame/Axis syntax #4521
  params.Frame: Add parameters 'fill' for filling the base map #4520
• examples/gallery/histograms/rose.py
  DOC/Gallery example "Rose diagram": Migrate frame settings to the new Frame/Axis syntax #4522
• examples/gallery/histograms/scatter_and_histograms.py
  DOC/Gallery example "Scatter plot with histograms": Migrate frame settings to the new Frame/Axis syntax #4523
• examples/gallery/images/cross_section.py
• examples/gallery/images/grdclip.py
• examples/gallery/images/grdgradient_shading.py
• examples/gallery/images/grdgradient.py
• examples/gallery/images/rgb_image.py
• examples/gallery/lines/connection_lines.py
• examples/gallery/lines/envelope.py
• examples/gallery/lines/hlines_vlines.py
• examples/gallery/lines/line_custom_cpt.py
• examples/gallery/lines/wiggle.py
• examples/gallery/seismology/velo_arrow_ellipse.py
• examples/gallery/symbols/datetime_inputs.py
• examples/gallery/symbols/multi_parameter_symbols.py
• examples/gallery/symbols/points_categorical.py
• examples/gallery/symbols/points_transparency.py
• examples/gallery/symbols/scatter.py
• examples/intro/01_first_figure.py
• examples/intro/03_figure_element.py
• examples/projections/nongeo/cartesian_linear.py
• examples/projections/nongeo/cartesian_logarithmic.py
• examples/projections/nongeo/cartesian_power.py
• examples/projections/nongeo/polar.py
• examples/tutorials/advanced/3d_perspective_image.py
• examples/tutorials/advanced/cartesian_histograms.py
• examples/tutorials/advanced/date_time_charts.py
• examples/tutorials/advanced/grid_equalization.py
• examples/tutorials/advanced/non_ascii_text.py
• examples/tutorials/advanced/subplots.py
• examples/tutorials/basics/frames.py
• examples/tutorials/basics/text.py
• pygmt/helpers/testing.py
• pygmt/src/colorbar.py
• pygmt/src/grdview.py
• pygmt/tests/test_alias_system.py
• pygmt/tests/test_basemap.py
• pygmt/tests/test_config.py
• pygmt/tests/test_geopandas.py
• pygmt/tests/test_grdview.py DOC/Test "test_grdview": Migrate frame settings to the new Frame/Axis syntax #4532
• pygmt/tests/test_helpers.py DOC/Test "test_helper": Migrate frame settings to the new Frame/Axis syntax #4530
• pygmt/tests/test_plot.py DOC/Test "test_plot": Migrate frame settings to the new Frame/Axis syntax #4526
• pygmt/tests/test_plot3d.py DOC/Test "test_plot3d": Migrate frame settings to the new Frame/Axis syntax #4519
• pygmt/tests/test_rose.py DOC/Test "test_rose": Migrate frame settings to the new Frame/Axis syntax #4518
• pygmt/tests/test_ternary.py
• pygmt/tests/test_text.py DOC/Test "test_text": Migrate frame settings to the new Frame/Axis syntax #4516
• pygmt/tests/test_velo.py DOC/Test "test_velo": Migrate frame settings to the new Frame/Axis syntax #4515