在Matplotlib极坐标图上设置径向轴

Question

我正在极坐标图上绘制方位角高程曲线,其中高程是径向分量.默认情况下,Matplotlib将径向值从中心的0绘制到周长的90.我想扭转局面,因此90度处于中心位置.我尝试通过调用ax.set_ylim(90,0)设置限制,但这会导致抛出LinAlgError异常.ax是从调用add_axes获得的轴对象.

可以这样做,如果是这样,我该怎么办？

编辑:这是我现在正在使用的.基本绘图代码取自Matplotlib示例中的一个

# radar green, solid grid lines
rc('grid', color='#316931', linewidth=1, linestyle='-')
rc('xtick', labelsize=10)
rc('ytick', labelsize=10)

# force square figure and square axes looks better for polar, IMO
width, height = matplotlib.rcParams['figure.figsize']
size = min(width, height)
# make a square figure
fig = figure(figsize=(size, size))
ax = fig.add_axes([0.1, 0.1, 0.8, 0.8], projection='polar', axisbg='#d5de9c')

# Adjust radius so it goes 90 at the center to 0 at the perimeter (doesn't work)
#ax.set_ylim(90, 0)

# Rotate plot so 0 degrees is due north, 180 is due south

ax.set_theta_zero_location("N")

obs.date = datetime.datetime.utcnow()
az,el = azel_calc(obs, ephem.Sun())
ax.plot(az, el, color='#ee8d18', lw=3)
obs.date = datetime.datetime.utcnow()
az,el = azel_calc(obs, ephem.Moon())
ax.plot(az, el, color='#bf7033', lw=3)

ax.set_rmax(90.)
grid(True)

ax.set_title("Solar Az-El Plot", fontsize=10)
show()

由此产生的情节是

Answer 1

我设法将他的径向轴倒置。我必须重新映射半径，以匹配新轴：

fig = figure()
ax = fig.add_subplot(1, 1, 1, polar=True)

def mapr(r):
   """Remap the radial axis."""
   return 90 - r

r = np.arange(0, 90, 0.01)
theta = 2 * np.pi * r / 90

ax.plot(theta, mapr(r))
ax.set_yticks(range(0, 90, 10))                   # Define the yticks
ax.set_yticklabels(map(str, range(90, 0, -10)))   # Change the labels

请注意，这只是一个 hack，轴仍然以 0 为中心，90 为周边。您必须对要绘制的所有变量使用映射函数。