`tricontour`

Draw contour lines of a field defined on a triangulation of scattered points.

Matplotlib: Axes.tricontour.

Axes: rectangular (ax) and ternary (axtri).

Coordinates

Key	Required	Meaning
`x`	yes¹	Point x
`y`	yes¹	Point y
`z`	yes	Value per point

¹ On a ternary axis use left / right / bottom instead of x / y.

Style

Key	Type	Purpose
`levels`	int or list	Number of levels, or explicit values
`colors`	color list	One color per level
`linewidths`	float list	One width per level
`linestyles`	string/list	Line styles
`cmap`	string	Color levels by colormap (instead of `colors`)
`zorder`	number	Draw order

Any other Axes.tricontour keyword is also accepted.

Example (ternary)

- name: tri
  data:
    - source: df
  axes: axtri
  method: tricontour
  coordinates:
    left:   {expr: a}
    right:  {expr: b}
    bottom: {expr: c}
    z:      {expr: z}
  style:
    levels: 20
    colors: ["0.0", "0.5"]
    linewidths: [1.0, 0.5]
    zorder: 10