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
r - Adding Contour Lines to 3D Plots - Stack Overflow
Scatter plot using Plotly in Python - GeeksforGeeks
Contour plot includes negative values when my dataset is positive using plotly in R - Stack Overflow