Ternary diagram

The pygmt.Figure.ternary method can draw ternary diagrams. The example shows how to plot circles with a diameter of 0.1 centimeters (style="c0.1c") on a 10-centimeters-wide (width="10c") ternary diagram at the positions listed in the first three columns of the sample dataset rock_compositions, with default annotations and gridline spacings, using the specified labeling defined via alabel, blabel, and clabel. Points are colored based on the values given in the fourth columns of the sample dataset via cmap=True.

import pygmt

fig = pygmt.Figure()

# Load sample data
data = pygmt.datasets.load_sample_data(name="rock_compositions")

# Define a colormap to be used for the values given in the fourth column
# of the input dataset
pygmt.makecpt(cmap="batlow", series=[0, 80, 10])

fig.ternary(
    data,
    region=[0, 100, 0, 100, 0, 100],
    width="10c",
    style="c0.1c",
    alabel="Limestone",
    blabel="Water",
    clabel="Air",
    cmap=True,
    frame=[
        "aafg+lLimestone component+u %",
        "bafg+lWater component+u %",
        "cafg+lAir component+u %",
    ],
)

# Add a colorbar indicating the values given in the fourth column of
# the input dataset
fig.colorbar(position="JBC+o0c/1.5c", frame="x+lPermittivity")
fig.show()