# -*-Python-*-
# Created by bgrierson at 17 Feb 2017 17:14
"""
======================================
Radar chart (aka spider or star chart)
======================================
This example creates a radar chart, also known as a spider or star chart [1]_.
Although this example allows a frame of either 'circle' or 'polygon', polygon
frames don't have proper gridlines (the lines are circles instead of polygons).
It's possible to get a polygon grid by setting GRIDLINE_INTERPOLATION_STEPS in
matplotlib.axis to the desired number of vertices, but the orientation of the
polygon is not aligned with the radial axes.
.. [1] http://en.wikipedia.org/wiki/Radar_chart
"""
from matplotlib.path import Path
from matplotlib.spines import Spine
from matplotlib.projections.polar import PolarAxes
from matplotlib.projections import register_projection
def unit_poly_verts(theta):
"""Return vertices of polygon for subplot axes.
This polygon is circumscribed by a unit circle centered at (0.5, 0.5)
"""
x0, y0, r = [0.5] * 3
verts = [(r * np.cos(t) + x0, r * np.sin(t) + y0) for t in theta]
return verts
def radar_factory(num_vars, frame='circle'):
"""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)
# rotate theta such that the first axis is at the top
theta += np.pi / 2
def draw_poly_patch(self):
verts = unit_poly_verts(theta)
return plt.Polygon(verts, closed=True, edgecolor='k')
def draw_circle_patch(self):
# unit circle centered on (0.5, 0.5)
return plt.Circle((0.5, 0.5), 0.5)
patch_dict = {'polygon': draw_poly_patch, 'circle': draw_circle_patch}
if frame not in patch_dict:
raise ValueError('unknown value for `frame`: %s' % frame)
class RadarAxes(PolarAxes):
name = 'radar'
# use 1 line segment to connect specified points
RESOLUTION = 1
# define draw_frame method
draw_patch = patch_dict[frame]
def fill(self, *args, **kwargs):
"""Override fill so that line is closed by default"""
closed = kwargs.pop('closed', True)
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)
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.concatenate((x, [x[0]]))
y = np.concatenate((y, [y[0]]))
line.set_data(x, y)
def set_varlabels(self, labels):
self.set_thetagrids(np.degrees(theta), labels)
def _gen_axes_patch(self):
return self.draw_patch()
def _gen_axes_spines(self):
if frame == 'circle':
return PolarAxes._gen_axes_spines(self)
# The following is a hack to get the spines (i.e. the axes frame)
# to draw correctly for a polygon frame.
# spine_type must be 'left', 'right', 'top', 'bottom', or `circle`.
spine_type = 'circle'
verts = unit_poly_verts(theta)
# close off polygon by repeating first vertex
verts.append(verts[0])
path = Path(verts)
spine = Spine(self, spine_type, path)
spine.set_transform(self.transAxes)
return {'polar': spine}
register_projection(RadarAxes)
return theta
# Data in absolute units
target = np.array([3.1, 1.8, 0.1, 2.0, 0.4])
shot = np.array([3.5, 2.1, 0.11, 2.2, 0.36])
data = [['q95', 'betan', 'tinj', 'H89', 'G'], ('IBS', target), ('shot', shot)]
spoke_labels = data.pop(0)
N = len(spoke_labels)
theta = radar_factory(N, frame='circle')
fig, ax = plt.subplots(subplot_kw=dict(projection='radar'))
ax.set_rgrids(arange(0.5, 3.5, 0.5))
ax.plot(theta, data[0][1])
ax.plot(theta, data[1][1])
ax.set_varlabels(spoke_labels)
# Data in deviation from target
data = [['q95', 'betan', 'tinj', 'H89', 'G'], ('IBS', target / target), ('shot', shot / target)]
spoke_labels = data.pop(0)
N = len(spoke_labels)
theta = radar_factory(N, frame='circle')
fig, ax = plt.subplots(subplot_kw=dict(projection='radar'))
ax.set_rgrids(np.array([0.5, 1.0, 1.5]))
ax.plot(theta, data[0][1])
ax.fill(theta, data[0][1], facecolor='b', alpha=0.25)
ax.plot(theta, data[1][1])
ax.fill(theta, data[1][1], facecolor='g', alpha=0.25)
ax.set_varlabels(spoke_labels)
ax.set_rlim([0, 2])
