matplotlib 雷达图/蛛网图

本篇讲解如何用matplotlib 画雷达图(蛛网图)。

第一个例子来自matplotlib官网,封装比较多,看起来有点复杂,但本质上是在极坐标系下画封闭的曲线图。

代码如下:

"""
======================================
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.
.. [1] http://en.wikipedia.org/wiki/Radar_chart
"""
import numpy as np
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

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)#角度(弧度制)
    def draw_poly_patch(self):
        # rotate theta such that the first axis is at the top
        verts = unit_poly_verts(theta + np.pi / 2)
        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) #画圆
    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 __init__(self, *args, **kwargs):
            super(RadarAxes, self).__init__(*args, **kwargs)
            # rotate plot such that the first axis is at the top
            self.set_theta_zero_location('N')
        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 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)
        def _close_line(self, line):#使曲线封闭,首尾相连
            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 + np.pi / 2)
            # 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

def example_data():
    # The following data is from the Denver Aerosol Sources and Health study.
    # See  doi:10.1016/j.atmosenv.2008.12.017
    #
    # The data are pollution source profile estimates for five modeled
    # pollution sources (e.g., cars, wood-burning, etc) that emit 7-9 chemical
    # species. The radar charts are experimented with here to see if we can
    # nicely visualize how the modeled source profiles change across four
    # scenarios:
    #  1) No gas-phase species present, just seven particulate counts on
    #     Sulfate
    #     Nitrate
    #     Elemental Carbon (EC)
    #     Organic Carbon fraction 1 (OC)
    #     Organic Carbon fraction 2 (OC2)
    #     Organic Carbon fraction 3 (OC3)
    #     Pyrolized Organic Carbon (OP)
    #  2)Inclusion of gas-phase specie carbon monoxide (CO)
    #  3)Inclusion of gas-phase specie ozone (O3).
    #  4)Inclusion of both gas-phase species is present...
    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]]),
        ('With CO', [
            [0.88, 0.02, 0.02, 0.02, 0.00, 0.05, 0.00, 0.05, 0.00],
            [0.08, 0.94, 0.04, 0.02, 0.00, 0.01, 0.12, 0.04, 0.00],
            [0.01, 0.01, 0.79, 0.10, 0.00, 0.05, 0.00, 0.31, 0.00],
            [0.00, 0.02, 0.03, 0.38, 0.31, 0.31, 0.00, 0.59, 0.00],
            [0.02, 0.02, 0.11, 0.47, 0.69, 0.58, 0.88, 0.00, 0.00]]),
        ('With O3', [
            [0.89, 0.01, 0.07, 0.00, 0.00, 0.05, 0.00, 0.00, 0.03],
            [0.07, 0.95, 0.05, 0.04, 0.00, 0.02, 0.12, 0.00, 0.00],
            [0.01, 0.02, 0.86, 0.27, 0.16, 0.19, 0.00, 0.00, 0.00],
            [0.01, 0.03, 0.00, 0.32, 0.29, 0.27, 0.00, 0.00, 0.95],
            [0.02, 0.00, 0.03, 0.37, 0.56, 0.47, 0.87, 0.00, 0.00]]),
        ('CO & O3', [
            [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]])
    ]
    return data

if __name__ == '__main__':
    N = 9
    theta = radar_factory(N, frame='polygon')
    data = example_data()
    spoke_labels = data.pop(0)
    fig, axes = plt.subplots(figsize=(9, 9), nrows=2, ncols=2,
                             subplot_kw=dict(projection='radar'))
    fig.subplots_adjust(wspace=0.25, hspace=0.20, top=0.85, bottom=0.05)
    colors = ['b', 'r', 'g', 'm', 'y']
    # Plot the four cases from the example data on separate axes
    for ax, (title, case_data) in zip(axes.flatten(), data):
        ax.set_rgrids([0.2, 0.4, 0.6, 0.8])
        ax.set_title(title, weight='bold', size='medium', position=(0.5, 1.1),
                     horizontalalignment='center', verticalalignment='center')
        for d, color in zip(case_data, colors):
            ax.plot(theta, d, color=color) ##本质是在极坐标下画封闭曲线
            ax.fill(theta, d, facecolor=color, alpha=0.25)##填充
        ax.set_varlabels(spoke_labels)
    # add legend relative to top-left plot
    ax = axes[0, 0]
    labels = ('Factor 1', 'Factor 2', 'Factor 3', 'Factor 4', 'Factor 5')
    legend = ax.legend(labels, loc=(0.9, .95),
                       labelspacing=0.1, fontsize='small')
    fig.text(0.5, 0.965, '5-Factor Solution Profiles Across Four Scenarios',
             horizontalalignment='center', color='black', weight='bold',
             size='large')
    plt.show()
    

第二个例子来自罗兵の水库的博客。因原代码在我电脑上有bug,不能完整显示图形,已更正,还略做了简化。

代码如下:

'''
matplotlib雷达图
'''
import numpy as np
import matplotlib.pyplot as plt

# 雷达图
def plot_radar(labels, data, score):
    n = len(labels)
    # 转化为十分制!!!
    if score in [5, 10, 100]:
        data = data * 10/score
    elif score == 1:
        data = data * 10  
    angles = np.linspace(0, 2*np.pi, n, endpoint=False) 
    data = np.concatenate((data, [data[0]])) # 闭合
    angles = np.concatenate((angles, [angles[0]])) # 闭合
    
    fig = plt.figure()
    ax = fig.add_subplot(111, polar=True)# 参数polar,表示极坐标!!
    # 画grid线(5条环形线)
    for i in [2,4,6,8,10]:
        ax.plot(angles, [i]*(n+1), 'k-',lw=0.5,) # 之所以 n +1,是因为要闭合!
    
     # 填充底色
    ax.fill(angles, [10]*(n+1), facecolor='lightgreen', alpha=0.2)
    # 自己画grid线(n条半径线)
    for i in range(n):
        ax.plot([angles[i], angles[i]], [0, 10], 'b-',lw=0.5)
        
    # 画线(数据)!
    ax.set_theta_zero_location( "N")#从正上方开始(对称比较美@_@)
    #ax.set_theta_zero_location(self, loc, offset=0.0), loc May be one of "N", "NW", "W", "SW", "S", "SE", "E", or "NE".
    ax.plot(angles, data, 'b-', linewidth=2,marker = "o", markersize =5)
    # 填充
    ax.fill(angles, data, facecolor='r', alpha=1.0)

    grid_angles = [ i* 360.0/n for i in range(n)]
    ax.set_thetagrids(grid_angles, labels, fontproperties="SimHei") #grid_angles是角度制!!
    ax.set_title("matplotlib雷达图", va='bottom', fontproperties="SimHei", fontsize =14,color="g")
    
    ax.set_rlim(0,10)
    # 下两行去掉所有默认的grid线
    ax.spines['polar'].set_visible(False) # 去掉最外围的黑圈
    ax.grid(False)                        # 去掉中间的黑圈

    ax.set_yticks([])# 关闭径向数值刻度
    plt.show()
    
if __name__ == '__main__':
    labels = np.array(['水','火','风','云','雷','电']) #标签
    data = np.array([95,60,80,60,70,88]) # 数据
    score = 100 # 其可选的选项有1分制、5分制、10分制、100分制
    # 画雷达图
    plot_radar(labels, data, score)

原文发布于微信公众号 - Python编程 pyqt matplotlib(wsplovePython)

原文发表时间:2019-05-06

本文参与腾讯云自媒体分享计划,欢迎正在阅读的你也加入,一起分享。

发表于

我来说两句

0 条评论
登录 后参与评论

扫码关注云+社区

领取腾讯云代金券