如何在每个象限中绘制一个半径不同的圆？

Question

我想绘制一个类似于以下示例的形状（来自 Naval Research Laboratory TC 页面）。形状由 4 个半径定义，每个象限一个。

我在经纬度坐标中有多个轨迹中心，我使用 Basemap 绘制这些轨迹中心：

def m_plot_wind_speeds(x,y, mps):

    # There's a switch-like statement here to determine the color of the
    # line based on wind speed which I ignored. This is passed to the 
    # color kwarg in m.plot as cur_color. 

    m.plot(x,y, '.-', markersize=ms, linewidth=lw, color=cur_color, \
 mew=1.5, markerfacecolor='k')

m = Basemap(projection='cyl',area_thresh=1000, \
    llcrnrlat=southLat,urcrnrlat=northLat,llcrnrlon=westLong,urcrnrlon=eastLong,resolution='h')
parallels = np.arange(southLat,northLat+10,10.) # make latitude lines ever 5 degrees from 30N-50N
meridians = np.arange(westLong,eastLong+30,30.) # make longitude lines every 5 degrees from 95W to 70W

m.drawparallels(parallels,labels=[1,0,0,0],labelstyle="+/-", linewidth=0, fontsize=6)
m.drawmeridians(meridians,labels=[0,0,0,1],labelstyle="+/-", linewidth=0, fontsize=6)
m.drawcountries(linewidth=0.25)

m.bluemarble()

# data is a [10]x[~]x[10] list. There are 10 trajectories, each with
# varying lengths. Each trajectory has 10 attributes.

for traj in data:
    lat = []
    lon = []
    wind_speed=[]

    for i in traj:
        lat.append(float(i[1]))
        lon.append(float(i[0]))
        wind_speed.append(float(i[2]))

   for j,var in enumerate(traj):
        if j > 0:
            x,y = m([lon[j], lon[j-1]], [lat[j], lat[j-1]])
        else:
            x,y = m([lon[j], lon[j]],[lat[j], lat[j]])
        m_plot_wind_speeds(x,y,wind_speed[j])


        # TODO: Insert a function here that takes in a 4 radii and plots them 
        # in each quadrant.

Answer 1

如果您不介意线条朝向中心，可以使用wedges。

或者，使用arcs、hlines 和vlines，可以绘制轮廓。你仍然需要楔形或特制的多边形来填充。

import numpy as np
from matplotlib import patches
import matplotlib.pyplot as plt

def draw_quadrants_arcs(xcenter, ycenter, radii, lw=2, ec='crimson', ax=None):
    ax = ax or plt.gca()
    for rad, theta in zip(radii, [0, 90, 180, 270]):
        arc = patches.Arc((xcenter, ycenter), 2*rad, 2*rad, theta1=theta, theta2=theta+90,
                              lw=lw, ec=ec, fc='none')
        ax.add_patch(arc)
    ax.hlines([ycenter, ycenter], [xcenter + radii[0], xcenter - radii[1]], [xcenter + radii[3], xcenter - radii[2]],
              lw=lw, colors=ec)
    ax.vlines([xcenter, xcenter], [ycenter + radii[0], ycenter - radii[2]], [ycenter + radii[1], ycenter - radii[3]],
              lw=lw, colors=ec)

def draw_quadrants_wedges(xcenter, ycenter, radii, lw=2, ec='crimson', fc='lime', alpha=1, ax=None):
    ax = ax or plt.gca()
    for rad, theta in zip(radii, [0, 90, 180, 270]):
        wedge = patches.Wedge((xcenter, ycenter), rad, theta, theta + 90,
                              lw=lw, ec=ec, fc=fc, alpha=alpha)
        ax.add_patch(wedge)

xcenter, ycenter = 6, 10
radii = [6, 2, 4, 7]
# only wedges
draw_quadrants_wedges(xcenter, ycenter, radii)
# only arcs
draw_quadrants_arcs(xcenter+12, ycenter, radii)
# wedges and arcs together
draw_quadrants_wedges(xcenter+24, ycenter, radii, ec='none', lw=0, fc='limegreen', alpha=0.3)
draw_quadrants_arcs(xcenter+24, ycenter, radii)

plt.xlim(0, 40)
plt.ylim(0, 20)
plt.gca().set_aspect('equal', 'box')
plt.show()