Fixed

• Fix hex_to_rgb parsing of 3-digit shorthand hexadecimal colors such as #FFF [#5662], with thanks to @genrichez for the contribution!
• Improve px.*_map() auto-fitting behavior when zoom and center are not specified [#5686]
• Add <!doctype html> to the to_html() template to comply with modern web standards [#5693], with thanks to @mishrakushal for the contribution!
• Apply histfunc/z aggregation to marginal_x/marginal_y="histogram" subplots in density_heatmap/density_contour, instead of always showing raw bin counts [#3521], with thanks to @lucasjamar for the contribution!
• Fix mpl_to_plotly silently dropping matplotlib path collections in data coordinates (such as violin plots, pcolor, event plots, stack plots, fill_between, and stem plots) by rendering them as filled polygons or lines [#5702], with thanks to @robertoffmoura for the contribution!

Removed

• Remove the deprecated Figure Factory functions create_2d_density, create_annotated_heatmap, create_bullet, create_candlestick, create_choropleth, create_distplot, create_facet_grid, create_gantt, create_hexbin_mapbox, create_ohlc, create_scatterplotmatrix, and create_violin [#5627]
• Remove support for Kaleido versions less than v1.0.0 for static image generation [#5677]
• Remove support for Orca for static image generation [#5677]
• Remove engine argument from functions fig.write_image(),fig.to_image(), pio.write_image(), pio.write_images(), pio.to_image(), pio.full_figure_for_development(), and from renderer constructors [#5677]

Updated

• Update plotly.js from version 3.6.0 to version 4.0.0 [#5673]. This is a major-version release with many changes. See the plotly.js release notes for the full list. The most significant changes include:
  • Add quiver trace type to visualize vector fields using arrows [#7710, #7945]
  • Add "Share Chart" modebar button for generating a chart-sharing link via Plotly Cloud [#7909]
  • Remove scattermapbox, choroplethmapbox, densitymapbox trace types, the mapbox subplot, and the mapboxAccessToken config option [#7860]. Use the equivalent *map traces instead.
    • The corresponding graph_objects and Plotly Express functions have also been removed in plotly.py; use the map versions instead
  • Drop support for MathJax v2, and add support for v4 [#7898]. MathJax is the JavaScript library used for rendering mathematical equations in plotly charts.
  • Switch color processing library from TinyColor to culori [#7536, #7962]. There are some changes to supported color string formats as a result:
    • rgb()/rgba() strings with decimal 0–1 fractions are no longer supported
    • hsv() color strings are no longer supported
    • Strings with invalid syntax such as hsl(120, 50% 50%) are no longer supported
    • New supported formats: '#ff0000aa', '#f00a', 'rgb(255 0 0)', 'rgba(255 0 0 / 0.5)', 'hsl(0 100% 50% / 0.5)', 'hsla(0, 100%, 50%, 0.5)', 'hwb(0, 0%, 0%)', lab(), lch(), oklab(), oklch(), color(), hsl(0.5turn 60% 40%), hsl(none 60% 40%)
  • Replace country-regex with country-iso-search to search for country names in choropleth, scattergeo traces [#7856]. Most country names are handled exactly the same; a small number of legacy entries have been removed.
  • Change layout.geo.fitbounds default from false to 'locations' [#7895]. geo subplots will now auto-fit the initial view to the trace data by default.
  • Dynamically compute center and zoom values for scattermap and densitymap traces. The initial map view will now auto-fit to the trace data by default. Add layout.map.fitbounds attribute (default 'locations') to enable or disable auto-fitting behavior [#7884, #7913]
  • Fix GeoJSON bounding-box computation for choropleth and scattergeo traces whose geometry crosses the antimeridian [#7891]