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I'm trying to learn how radar charts work in matplotlib. I'm using the code in this thread, but the plot I'm producing is not rightly centered and there are axis missing. I' ve tried with matplotlib 1.3.1, 1.4.1 and 1.5.1 in case something changed in the last versions.

enter image description here

import numpy as np
import pylab as pl

class Radar(object):

    def __init__(self, fig, titles, labels, rect=None):
        if rect is None:
            rect = [0.05, 0.05, 0.95, 0.95]

        self.n = len(titles)
        self.angles = np.arange(90, 90+360, 360.0/self.n)
        self.axes = [fig.add_axes(rect, projection="polar", label="axes%d" % i) 
                         for i in range(self.n)]

        self.ax = self.axes[0]
        self.ax.set_thetagrids(self.angles, labels=titles, fontsize=14)

        for ax in self.axes[1:]:
            ax.patch.set_visible(False)
            ax.grid("off")
            ax.xaxis.set_visible(False)

        for ax, angle, label in zip(self.axes, self.angles, labels):
            ax.set_rgrids(range(1, 6), angle=angle, labels=label)
            ax.spines["polar"].set_visible(False)
            ax.set_ylim(0, 5)

    def plot(self, values, *args, **kw):
        angle = np.deg2rad(np.r_[self.angles, self.angles[0]])
        values = np.r_[values, values[0]]
        self.ax.plot(angle, values, *args, **kw)



fig = pl.figure(figsize=(6, 6))

titles = list("ABCDE")

labels = [
    list("abcde"), list("12345"), list("uvwxy"), 
    ["one", "two", "three", "four", "five"],
    list("jklmn")
]

radar = Radar(fig, titles, labels)
radar.plot([1, 3, 2, 5, 4],  "-", lw=2, color="b", alpha=0.4, label="first")
radar.plot([2.3, 2, 3, 3, 2],"-", lw=2, color="r", alpha=0.4, label="second")
radar.plot([3, 4, 3, 4, 2], "-", lw=2, color="g", alpha=0.4, label="third")
radar.ax.legend()
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FranGoitia
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1 Answers1

4

I had the same problem, but I found that the problem was the following part:

self.angles = np.arange(90, 90+360, 360.0/self.n)

So change it to

self.angles = np.arange(0, 360, 360.0/self.n)

and rotate each ax with ax.set_theta_offset(np.deg2rad(90)) instead.

The modified class looks like this:

# Python 3.4
# matplotlib 1.5.3
class Radar(object):
    def __init__(self, fig, titles, labels, rotation=0, rect=None):
        if rect is None:
            rect = [0.05, 0.05, 0.95, 0.95]

        self.n = len(titles)
        self.angles = np.arange(0, 360, 360.0/self.n)
        self.axes = [fig.add_axes(rect, projection="polar", label="axes%d" % i) 
                         for i in range(self.n)]

        self.ax = self.axes[0]
        self.ax.set_thetagrids(self.angles, labels=titles, fontsize=14)

        for ax in self.axes[1:]:
            ax.patch.set_visible(False)
            ax.grid("off")
            ax.xaxis.set_visible(False)

        for ax, angle, label in zip(self.axes, self.angles, labels):
            ax.set_rgrids(range(1, 6), angle=angle, labels=label)
            ax.spines["polar"].set_visible(False)
            ax.set_ylim(0, 6)
            ax.set_theta_offset(np.deg2rad(rotation))

    def plot(self, values, *args, **kw):
        angle = np.deg2rad(np.r_[self.angles, self.angles[0]])
        values = np.r_[values, values[0]]
        self.ax.plot(angle, values, *args, **kw)

Note: I've added the parameter rotation=0 to __init__ and apply the rotation to all ax in the last loop of it.

I know it's been a while since the question was asked, but I assume someone else will stumble upon this.

Thomas Fauskanger
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