```# -*-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.

"""

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

"""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)

# 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}

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)

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)