"""Petal diagram visualization for multi-objective optimization."""
import numpy as np
from pymoo.core.plot import Plot
from pymoo.util.misc import set_if_none
from pymoo.visualization.util import (
equal_axis,
get_circle_points,
no_ticks,
normalize,
parse_bounds,
plot_axes_lines,
plot_axis_labels,
plot_circle,
plot_polygon,
)
[docs]
class Petal(Plot):
"""Petal diagram for multi-objective visualization."""
def __init__(
self,
bounds=None,
**kwargs,
):
"""Initialize Petal diagram.
Args:
bounds: The boundaries for each objective. Necessary to be provided for this plot!
**kwargs: Additional keyword arguments passed to parent Plot class.
"""
super().__init__(bounds=bounds, **kwargs)
if bounds is None:
raise Exception(
"Boundaries must be provided for Petal Width. Otherwise, no trade-offs can be calculated."
)
set_if_none(self.axis_style, "color", "black")
set_if_none(self.axis_style, "linewidth", 2)
set_if_none(self.axis_style, "alpha", 0.5)
def _plot(self, ax, F):
# equal axis length and no ticks
equal_axis(ax)
no_ticks(ax)
V = get_circle_points(len(F))
# sections to plot
sections = np.linspace(0, 2 * np.pi, self.n_dim + 1)
t = [(sections[i] + sections[i + 1]) / 2 for i in range(len(sections) - 1)]
endpoints = np.column_stack([np.cos(t), np.sin(t)])
plot_axis_labels(ax, endpoints, self.get_labels(), **self.axis_label_style)
center = np.zeros(2)
for i in range(len(sections) - 1):
t = np.linspace(sections[i], sections[i + 1], 100)
v = np.column_stack([np.cos(t), np.sin(t)])
P = np.vstack([center, F[i] * v])
plot_polygon(ax, P, color=self.colors[i])
# draw the outer circle
plot_circle(ax, **self.axis_style)
plot_axes_lines(ax, V, **self.axis_style)
def _do(self):
n_rows = len(self.to_plot)
n_cols = max([len(e[0]) for e in self.to_plot])
self.init_figure(n_rows=n_rows, n_cols=n_cols, force_axes_as_matrix=True)
# normalize the input
bounds = parse_bounds(self.bounds, self.n_dim)
to_plot_norm = normalize(self.to_plot, bounds, reverse=self.reverse)
for k, (F, kwargs) in enumerate(to_plot_norm):
for j, _F in enumerate(F):
self._plot(self.ax[k, j], _F)
