radar_plot() wrapper function around matplotlib example

radar_plot.py

from __future__ import print_function
import matplotlib.pyplot as plt
from matplotlib.path import Path
from matplotlib.spines import Spine
from matplotlib.projections.polar import PolarAxes
from matplotlib.projections import register_projection
import numpy as np
import seaborn as sns

def radar_plot(data, feat_labels=[], line_labels=None, colors=None, ax=None, frame='circle', **kwargs):
    '''Create radar plot from 2D array. Each row is a closed line; each column is a feature/axis.
    
    Parameters
    ----------
    data        2D array with dimensions (samples, features)
    feat_labels names of features
    colors      list of mpl color codes for each sample
    line_labels list of labels for each line
    fill        bool: filles lines
    alpha       float 0 to 1: fill transparency
    '''
    num_samples = len(data)
    num_features = len(data[0])
    if colors is None:
       colors = sns.color_palette('spectral', num_samples)
    num_feat_lab, num_colors = len(feat_labels), len(colors)
    if num_feat_lab > 0 and num_features != num_feat_lab:
        raise ValueError('Number of features labels %d must match data features dimension %d' % (num_feat_lab,num_features))
    if num_colors > 0 and num_samples != num_colors:
        raise ValueError('Number of colors %d must match data samples dimension %d' % (num_colors,num_samples))

    theta = radar_factory(num_features, frame=frame)
    if not ax:
        fig = plt.figure()
        ax = fig.add_subplot(111, projection='radar')
    if line_labels is None:
        line_labels = ['%d' % (x+1) for x in range(num_samples)]
    ax.plotall(theta, data, feat_labels=feat_labels, line_labels=line_labels, colors=colors, **kwargs)
    legend = plt.legend(loc=(0.9, .95), labelspacing=0.1)
    plt.setp(legend.get_texts(), fontsize='small')
    return

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 = 2*np.pi * np.linspace(0, 1-1./num_vars, num_vars)
    # 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(RadarAxes, self).fill(closed=closed, *args, **kwargs)

        def plotall(self, theta, data, feat_labels=[], line_labels=[], colors=[], *args, **kwargs):
            from itertools import izip_longest
            fill = kwargs.pop('fill', True)
            alpha = kwargs.pop('alpha', .25)
            if colors and len(colors) != len(data):
                raise ValueError('color must be same length as data')
            for x,color,label in izip_longest(data, colors, line_labels):
                lines = self.plot(theta, x, label=label, color=color, *args, **kwargs)
                if fill:
                    c = color or lines[-1].get_color()
                    self.fill(theta, x, facecolor=c, alpha=alpha)
            if feat_labels:
                self.set_varlabels(feat_labels)
                
        def plot(self, *args, **kwargs):
            """Override plot so that line is closed by default"""
            lines = super(RadarAxes, self).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.concatenate((x, [x[0]]))
                y = np.concatenate((y, [y[0]]))
                line.set_data(x, y)

        def set_varlabels(self, line_labels):
            self.set_thetagrids(theta * 180/np.pi, line_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

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

if __name__ == '__main__':
    print("Radar plot test")
    fig = plt.figure()
    ax = fig.add_subplot(221, projection='radar')
    radar_plot([[0.87, 0.01, 0.08, 0.00, 0.00, 0.04, 0.00, 0.00, 0.01],
                 [0.09, 0.95, 0.02, 0.03, 0.00, 0.01, 0.13, 0.06, 0.00],
                 [0.01, 0.02, 0.71, 0.24, 0.13, 0.16, 0.00, 0.50, 0.00],
                 [0.01, 0.03, 0.00, 0.28, 0.24, 0.23, 0.00, 0.44, 0.88],
                 [0.02, 0.00, 0.18, 0.45, 0.64, 0.55, 0.86, 0.00, 0.16]]
               , feat_labels=['Sulfate', 'Nitrate', 'EC', 'OC1', 'OC2', 'OC3', 'OP', 'CO', 'O3']
               , fill=True, alpha=.25,
               ax=ax)