python - 如何在 python 中制作多边形雷达(蜘蛛)图

Question

import matplotlib.pyplot as plt
import numpy as np

labels=['Siege', 'Initiation', 'Crowd_control', 'Wave_clear', 'Objective_damage']
markers = [0, 1, 2, 3, 4, 5]
str_markers = ["0", "1", "2", "3", "4", "5"]

def make_radar_chart(name, stats, attribute_labels=labels,
                     plot_markers=markers, plot_str_markers=str_markers):

    labels = np.array(attribute_labels)

    angles = np.linspace(0, 2*np.pi, len(labels), endpoint=False)
    stats = np.concatenate((stats,[stats[0]]))
    angles = np.concatenate((angles,[angles[0]]))

    fig = plt.figure()
    ax = fig.add_subplot(111, polar=True)
    ax.plot(angles, stats, 'o-', linewidth=2)
    ax.fill(angles, stats, alpha=0.25)
    ax.set_thetagrids(angles * 180/np.pi, labels)
    plt.yticks(markers)
    ax.set_title(name)
    ax.grid(True)

    fig.savefig("static/images/%s.png" % name)

    return plt.show()

make_radar_chart("Agni", [2,3,4,4,5]) # example

基本上我希望图表是五边形而不是圆形。有人能帮忙吗。我正在使用 python matplotlib 保存图像，稍后将存储和显示。我希望我的图表具有第二张图片的形式

编辑:

    gridlines = ax.yaxis.get_gridlines()
    for gl in gridlines:
        gl.get_path()._interpolation_steps = 5

从下面的答案中添加这部分代码很有帮助。我得到这张图表。仍然需要弄清楚如何摆脱最外圈:

Answer 1

radar chart demo展示了如何制作雷达图。结果如下所示:

在这里，外部书脊是根据需要的多边形形状。然而，内部网格线是圆形的。因此，悬而未决的问题是如何使网格线的形状与书脊的形状相同。

这可以通过覆盖 draw 方法并将网格线的路径插值步长变量设置为 RadarAxes 类的变量数来完成。

gridlines = self.yaxis.get_gridlines()
for gl in gridlines:
    gl.get_path()._interpolation_steps = num_vars

完整示例:

import numpy as np

import matplotlib.pyplot as plt
from matplotlib.patches import Circle, RegularPolygon
from matplotlib.path import Path
from matplotlib.projections.polar import PolarAxes
from matplotlib.projections import register_projection
from matplotlib.spines import Spine
from matplotlib.transforms import Affine2D


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)

    class RadarAxes(PolarAxes):

        name = 'radar'

        def __init__(self, *args, **kwargs):
            super().__init__(*args, **kwargs)
            # rotate plot such that the first axis is at the top
            self.set_theta_zero_location('N')

        def fill(self, *args, closed=True, **kwargs):
            """Override fill so that line is closed by default"""
            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):
            # The Axes patch must be centered at (0.5, 0.5) and of radius 0.5
            # in axes coordinates.
            if frame == 'circle':
                return Circle((0.5, 0.5), 0.5)
            elif frame == 'polygon':
                return RegularPolygon((0.5, 0.5), num_vars,
                                      radius=.5, edgecolor="k")
            else:
                raise ValueError("unknown value for 'frame': %s" % frame)

        def draw(self, renderer):
            """ Draw. If frame is polygon, make gridlines polygon-shaped """
            if frame == 'polygon':
                gridlines = self.yaxis.get_gridlines()
                for gl in gridlines:
                    gl.get_path()._interpolation_steps = num_vars
            super().draw(renderer)


        def _gen_axes_spines(self):
            if frame == 'circle':
                return super()._gen_axes_spines()
            elif frame == 'polygon':
                # spine_type must be 'left'/'right'/'top'/'bottom'/'circle'.
                spine = Spine(axes=self,
                              spine_type='circle',
                              path=Path.unit_regular_polygon(num_vars))
                # unit_regular_polygon gives a polygon of radius 1 centered at
                # (0, 0) but we want a polygon of radius 0.5 centered at (0.5,
                # 0.5) in axes coordinates.
                spine.set_transform(Affine2D().scale(.5).translate(.5, .5)
                                    + self.transAxes)


                return {'polar': spine}
            else:
                raise ValueError("unknown value for 'frame': %s" % frame)

    register_projection(RadarAxes)
    return theta


data = [['Sulfate', 'Nitrate', 'EC', 'OC1', 'OC2', 'OC3', 'OP', 'CO', 'O3'],
        ('Basecase', [
            [0.88, 0.01, 0.03, 0.03, 0.00, 0.06, 0.01, 0.00, 0.00],
            [0.07, 0.95, 0.04, 0.05, 0.00, 0.02, 0.01, 0.00, 0.00],
            [0.01, 0.02, 0.85, 0.19, 0.05, 0.10, 0.00, 0.00, 0.00],
            [0.02, 0.01, 0.07, 0.01, 0.21, 0.12, 0.98, 0.00, 0.00],
            [0.01, 0.01, 0.02, 0.71, 0.74, 0.70, 0.00, 0.00, 0.00]])]

N = len(data[0])
theta = radar_factory(N, frame='polygon')

spoke_labels = data.pop(0)
title, case_data = data[0]

fig, ax = plt.subplots(figsize=(6, 6), subplot_kw=dict(projection='radar'))
fig.subplots_adjust(top=0.85, bottom=0.05)

ax.set_rgrids([0.2, 0.4, 0.6, 0.8])
ax.set_title(title,  position=(0.5, 1.1), ha='center')

for d in case_data:
    line = ax.plot(theta, d)
    ax.fill(theta, d,  alpha=0.25)
ax.set_varlabels(spoke_labels)

plt.show()