Ternary contours Plot using Plotly in Python

Last Updated : 01 Oct, 2020

A Plotly is a Python library that is used to design graphs, especially interactive graphs. It can plot various graphs and charts like histogram, barplot, boxplot, spreadplot, and many more. It is mainly used in data analysis as well as financial analysis. plotly is an interactive visualization library.

Ternary contours in Plotly

In plotly, ternary contours plot can be made by using the create_ternary_contour method of figure_factory class which helps to represent the isovalues lines which are defined inside the ternary diagram, where the sum of three variables is constant. It graphically depicts the ratios of the three variables as positions in an equilateral triangle.

Syntax: create_ternary_contour(coordinates, values, pole_labels=['a', 'b', 'c'],ncontours=None, interp_mode='ilr', showmarkers=False)

Example:

Python3

import plotly.figure_factory as ff
import numpy as np

test_data = np.array([[0, 0, 1, 0],
                      [0.25, 0.25, 0.5, 0],
                      [0.25, 0.25, 0.5, 0],
                      [0.25, 0.25, 0.5, 1],
                      [0.25, 0.5, 0.25, 1],
                      [0, 1, 0, 1]])

# barycentric coords: (a,b,c)
a = test_data[:, 0]
b = test_data[:, 1]
c = test_data[:, 2]

# values is stored in the last column
v = test_data[:, -1]

fig = ff.create_ternary_contour(
    np.array([a, b, c]), v,
    pole_labels=['A', 'B', 'C'],
)

fig.show()

Output:

Customizing ternary contour plot

Height, width, colorscale, and many other values can be customized by using the parameter provided by this function.

Example:

Python3

import plotly.figure_factory as ff
import numpy as np

test_data = np.array([[0, 0, 1, 0],
                      [0.25, 0.25, 0.5, 0],
                      [0.25, 0.25, 0.5, 0],
                      [0.25, 0.25, 0.5, 1],
                      [0.25, 0.5, 0.25, 1],
                      [0, 1, 0, 1]])

# barycentric coords: (a,b,c)
a = test_data[:, 0]
b = test_data[:, 1]
c = test_data[:, 2]

# values is stored in the last column
v = test_data[:, -1]

fig = ff.create_ternary_contour(
    np.array([a, b, c]), v,
    pole_labels=['A', 'B', 'C'],
    ncontours=20,
    colorscale='Greens',
    showscale=True,
    title='Ternary Contour Plot'
)

fig.show()

Output:

Ternary contour plot with data points and lines

Only lines can be shown by the parameter coloring and setting it to lines and data points can be shown by passing True to the showmarkers parameter.

Example:

Python3

import plotly.figure_factory as ff
import numpy as np

test_data = np.array([[0, 0, 1, 0],
                      [0.25, 0.25, 0.5, 0],
                      [0.25, 0.25, 0.5, 0],
                      [0.25, 0.25, 0.5, 1],
                      [0.25, 0.5, 0.25, 1],
                      [0, 1, 0, 1]])

# barycentric coords: (a,b,c)
a = test_data[:, 0]
b = test_data[:, 1]
c = test_data[:, 2]

# values is stored in the last column
v = test_data[:, -1]

fig = ff.create_ternary_contour(
    np.array([a, b, c]), v,
    pole_labels=['A', 'B', 'C'],
    ncontours=20,
    colorscale='Greens',
    showscale=True,
    title='Ternary Contour Plot',
    coloring='lines',
    showmarkers=True
)

fig.show()