plotly 4.7.1 now on CRAN - Carson's blog on R, RStudio, plotly, shiny, data visualization, statistics, etc
2d histogram contour in Python
R Plotly: Smaller markers in bubble plot - Stack Overflow
Chart::Plotly::Trace::Contour - The data from which contour lines are computed is set in `z`. Data in `z` must be a {2D array} of numbers. Say that `z` has N rows and M