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

def radar_plot(data, axes=[], colors=[], labels=[], 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, axes)
    axes    names of axes
    colors  list of mpl color codes for each sample
    labels  list of labels for each line
    fill    bool: filles lines
    alpha   float 0 to 1: fill transparency
    '''
    try:
        from pandas import DataFrame
        if isinstance(data, DataFrame):
            return radar_plot(data.values, axes=data.columns, labels=data.index, colors=colors, ax=ax, frame=frame, **kwargs)
    except ImportError:
        pass
    num_features = max(map(len, data))
    num_axes, num_colors, num_labels = len(axes), len(colors), len(labels)
    if num_axes > 0 and num_features != num_axes:
        raise ValueError('Number of named axes (%d) must match width of array (%d)' % (num_axes,num_features))
    if num_labels > 0 and num_labels != len(data):
        raise ValueError('Number of labels (%d) must equal length (number of rows) in data (%d)' % (len(labels),len(data)))
    if num_colors > 0 and len(data) != num_colors:
        raise ValueError('Number of colors (%d) must match data dimensions %d' % (num_colors,num_features))

    theta = radar_factory(num_features, frame=frame)
    if not ax:
        fig = plt.figure()
        ax = fig.add_subplot(111, projection='radar')
    return ax.plotall(theta, data, labels=labels, axes=axes, colors=colors, **kwargs)

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, colors=[], axes=[], labels=[], *args, **kwargs):
            from itertools import izip_longest
            fill = kwargs.pop('fill', kwargs.has_key('alpha'))
            alpha = kwargs.pop('alpha', 1.0)
            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, 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 len(axes) > 0:
                self.set_varlabels(axes)
                
        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, labels):
            self.set_thetagrids(theta * 180/np.pi, 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]]
               , axes=['Sulfate', 'Nitrate', 'EC', 'OC1', 'OC2', 'OC3', 'OP', 'CO', 'O3']
               , fill=True, alpha=.25,
               ax=ax)