A ternary plot displays three-component compositional data on an equilateral triangle where each vertex represents 100% of one component. Points inside the triangle show compositions that sum to a constant total (usually 100%), with position indicating relative proportions. This visualization is essential for data where three variables are interdependent and constrained to sum to a fixed value.
""" anyplot.ai
ternary-basic: Basic Ternary Plot
Library: pygal 3.1.0 | Python 3.13.13
Quality: 92/100 | Updated: 2026-05-06
"""
import math
import os
import cairosvg
import numpy as np
import pygal
from pygal.style import Style
THEME = os.getenv("ANYPLOT_THEME", "light")
PAGE_BG = "#FAF8F1" if THEME == "light" else "#1A1A17"
ELEVATED_BG = "#FFFDF6" if THEME == "light" else "#242420"
INK = "#1A1A17" if THEME == "light" else "#F0EFE8"
INK_SOFT = "#4A4A44" if THEME == "light" else "#B8B7B0"
INK_MUTED = "#6B6A63" if THEME == "light" else "#A8A79F"
BRAND = "#009E73"
np.random.seed(42)
H = math.sqrt(3) / 2
compositions = [
(65, 25, 10),
(10, 45, 45),
(30, 35, 35),
(40, 40, 20),
(50, 10, 40),
(20, 65, 15),
(90, 5, 5),
(5, 90, 5),
(5, 5, 90),
(33, 34, 33),
(45, 45, 10),
(55, 35, 10),
(15, 20, 65),
(10, 15, 75),
(50, 30, 20),
]
data_points = [(0.5 * (2 * s[1] + s[0]) / 100, H * s[0] / 100) for s in compositions]
vertex_sand = (0.5, H)
vertex_silt = (1.0, 0.0)
vertex_clay = (0.0, 0.0)
grid_lines = []
for pct in [0.2, 0.4, 0.6, 0.8]:
p1 = (0.5 * (2 * (1 - pct) + pct), H * pct)
p2 = (0.5 * pct, H * pct)
grid_lines.extend([p1, p2, (None, None)])
p1 = (0.5 * (2 * pct + (1 - pct)), H * (1 - pct))
p2 = (pct, 0.0)
grid_lines.extend([p1, p2, (None, None)])
p1 = (0.5 * (1 - pct), H * (1 - pct))
p2 = (0.5 * (2 * (1 - pct)), 0.0)
grid_lines.extend([p1, p2, (None, None)])
tick_marks = []
tick_len = 0.03
for pct in [0.2, 0.4, 0.6, 0.8]:
x_left = 0.5 * pct
y_left = H * pct
tick_marks.extend([(x_left, y_left), (x_left - tick_len, y_left), (None, None)])
x_right = 0.5 * (2 - pct)
y_right = H * pct
tick_marks.extend([(x_right, y_right), (x_right + tick_len, y_right), (None, None)])
x_base = pct
y_base = 0.0
tick_marks.extend([(x_base, y_base), (x_base, y_base - tick_len), (None, None)])
custom_style = Style(
background=PAGE_BG,
plot_background=PAGE_BG,
foreground=INK,
foreground_strong=INK,
foreground_subtle=INK_MUTED,
colors=(INK, INK_MUTED, BRAND, INK),
title_font_size=80,
label_font_size=48,
major_label_font_size=44,
legend_font_size=44,
value_font_size=40,
opacity=0.85,
)
chart = pygal.XY(
width=3600,
height=3600,
style=custom_style,
show_legend=True,
legend_at_bottom=True,
legend_at_bottom_columns=4,
show_x_guides=False,
show_y_guides=False,
show_x_labels=False,
show_y_labels=False,
x_title="",
y_title="",
title="Soil Composition · ternary-basic · pygal · anyplot.ai",
dots_size=20,
stroke=False,
include_x_axis=False,
xrange=(-0.15, 1.15),
yrange=(-0.20, 1.05),
explicit_size=True,
margin=50,
margin_bottom=120,
)
chart.add(
None, [vertex_clay, vertex_silt, vertex_sand, vertex_clay], stroke=True, show_dots=False, stroke_style={"width": 5}
)
chart.add(None, grid_lines, stroke=True, show_dots=False, stroke_style={"width": 2, "dasharray": "8,5"})
chart.add("Soil Samples", data_points, stroke=False, dots_size=22)
chart.add(None, tick_marks, stroke=True, show_dots=False, stroke_style={"width": 3})
svg_content = chart.render().decode("utf-8")
plot_x_start = 150
plot_x_end = 3450
plot_y_start = 250
plot_y_end = 3350
x_range = 1.30
y_range = 1.25
sand_px = plot_x_start + (0.5 + 0.15) / x_range * (plot_x_end - plot_x_start)
sand_py = plot_y_start + (1.05 - (H + 0.06)) / y_range * (plot_y_end - plot_y_start)
silt_px = plot_x_start + (1.07 + 0.15) / x_range * (plot_x_end - plot_x_start)
silt_py = plot_y_start + (1.05 - (-0.03)) / y_range * (plot_y_end - plot_y_start)
clay_px = plot_x_start + (-0.07 + 0.15) / x_range * (plot_x_end - plot_x_start)
clay_py = plot_y_start + (1.05 - (-0.03)) / y_range * (plot_y_end - plot_y_start)
vertex_labels_svg = f"""
<text x="{sand_px}" y="{sand_py}" text-anchor="middle" font-size="60" font-weight="bold" fill="{INK}" font-family="sans-serif">SAND</text>
<text x="{silt_px}" y="{silt_py}" text-anchor="start" font-size="60" font-weight="bold" fill="{INK}" font-family="sans-serif">SILT</text>
<text x="{clay_px}" y="{clay_py}" text-anchor="end" font-size="60" font-weight="bold" fill="{INK}" font-family="sans-serif">CLAY</text>
"""
pct_labels_svg = ""
pct_font_size = 36
for pct in [20, 40, 60, 80]:
frac = pct / 100.0
left_x = 0.5 * frac
left_y = H * frac
left_px = plot_x_start + (left_x - 0.06 + 0.15) / x_range * (plot_x_end - plot_x_start)
left_py = plot_y_start + (1.05 - left_y) / y_range * (plot_y_end - plot_y_start)
pct_labels_svg += f' <text x="{left_px}" y="{left_py}" text-anchor="end" font-size="{pct_font_size}" fill="{INK_MUTED}" font-family="sans-serif">{pct}</text>\n'
right_x = 0.5 * (2 - frac)
right_y = H * frac
right_px = plot_x_start + (right_x + 0.04 + 0.15) / x_range * (plot_x_end - plot_x_start)
right_py = plot_y_start + (1.05 - right_y) / y_range * (plot_y_end - plot_y_start)
pct_labels_svg += f' <text x="{right_px}" y="{right_py}" text-anchor="start" font-size="{pct_font_size}" fill="{INK_MUTED}" font-family="sans-serif">{pct}</text>\n'
base_x = frac
base_y = -0.05
base_px = plot_x_start + (base_x + 0.15) / x_range * (plot_x_end - plot_x_start)
base_py = plot_y_start + (1.05 - base_y) / y_range * (plot_y_end - plot_y_start)
pct_labels_svg += f' <text x="{base_px}" y="{base_py}" text-anchor="middle" font-size="{pct_font_size}" fill="{INK_MUTED}" font-family="sans-serif">{pct}</text>\n'
all_labels_svg = vertex_labels_svg + pct_labels_svg
svg_content = svg_content.replace("</svg>", all_labels_svg + "</svg>")
with open(f"plot-{THEME}.html", "w") as f:
f.write(svg_content)
cairosvg.svg2png(bytestring=svg_content.encode("utf-8"), write_to=f"plot-{THEME}.png")
Part of Basic Ternary Plot on anyplot.ai.