# -*- coding: utf-8 -*-
import numpy as np
from matplotlib.patches import Circle, RegularPolygon
from matplotlib.path import Path
from matplotlib.projections import register_projection
from matplotlib.projections.polar import PolarAxes
from matplotlib.spines import Spine
from matplotlib.transforms import Affine2D
[docs]
def radar_factory(num_vars, frame="circle"):
"""
This function is copied from https://matplotlib.org/stable/gallery/specialty_plots/radar_chart.html
Create a radar chart with `num_vars` axes.
This function creates a RadarAxes projection and registers it.
Parameters
----------
num_vars : int
Number of variables for radar chart.
frame : {'circle', 'polygon'}
Shape of frame surrounding axes.
"""
# calculate evenly-spaced axis angles
theta = np.linspace(0, 2 * np.pi, num_vars, endpoint=False)
class RadarTransform(PolarAxes.PolarTransform):
def transform_path_non_affine(self, path):
# Paths with non-unit interpolation steps correspond to gridlines,
# in which case we force interpolation (to defeat PolarTransform's
# autoconversion to circular arcs).
if path._interpolation_steps > 1:
path = path.interpolated(num_vars)
return Path(self.transform(path.vertices), path.codes)
class RadarAxes(PolarAxes):
name = "radar"
PolarTransform = RadarTransform
def __init__(self, *args, **kwargs):
super().__init__(*args, aspect="equal", **kwargs)
# rotate plot such that the first axis is at the top
self.set_theta_zero_location("N")
def fill(self, *args, closed=True, **kwargs):
"""Override fill so that line is closed by default"""
return super().fill(closed=closed, *args, **kwargs)
def plot(self, *args, **kwargs):
"""Override plot so that line is closed by default"""
lines = super().plot(*args, **kwargs)
for line in lines:
self._close_line(line)
return lines
def _close_line(self, line):
x, y = line.get_data()
# FIXME: markers at x[0], y[0] get doubled-up
if x[0] != x[-1]:
x = np.append(x, x[0])
y = np.append(y, y[0])
line.set_data(x, y)
def set_varlabels(self, labels, fontsize=12):
self.set_thetagrids(np.degrees(theta), labels, fontsize=fontsize)
def _gen_axes_patch(self):
# The Axes patch must be centered at (0.5, 0.5) and of radius 0.5
# in axes coordinates.
if frame == "circle":
return Circle((0.5, 0.5), 0.5)
elif frame == "polygon":
return RegularPolygon((0.5, 0.5), num_vars, radius=0.5, edgecolor="k")
else:
raise ValueError("Unknown value for 'frame': %s" % frame)
def _gen_axes_spines(self):
if frame == "circle":
return super()._gen_axes_spines()
elif frame == "polygon":
# spine_type must be 'left'/'right'/'top'/'bottom'/'circle'.
spine = Spine(
axes=self,
spine_type="circle",
path=Path.unit_regular_polygon(num_vars),
)
# unit_regular_polygon gives a polygon of radius 1 centered at
# (0, 0) but we want a polygon of radius 0.5 centered at (0.5,
# 0.5) in axes coordinates.
spine.set_transform(
Affine2D().scale(0.5).translate(0.5, 0.5) + self.transAxes
)
return {"polar": spine}
else:
raise ValueError("Unknown value for 'frame': %s" % frame)
register_projection(RadarAxes)
return theta