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I am attempting to plot two half polar charts beside each other using matplotlib, pandas and numpy. The plots are calles c30 and c31. c31 plots well on its own but c30 does not, it appears as a line as you can see in the picture. Also they sit on top of each other instead of side by side. Can anyone advise on how to solve this problem?

What I currently achieve:

import numpy as np
from scipy import interpolate
import pandas as pd
import matplotlib.pyplot as plt
c31df = pd.DataFrame({'measure':[0,7.52,7.91,8.57,8.9,8.94,9.36,9.21,7.97,6],      'angle':[0,52,60,75,90,110,120,135,150,180]})
c30df = pd.DataFrame({'measure':[0,5.1,7.26,7.58,8.1,8.46,8.51,8.9,8.94,7.87],  'angle':[0,52,60,75,90,110,120,135,150,180]})
c31x=c31df.measure[:-1] * np.cos(c31df.angle[:-1]/180*np.pi)
c31y=c31df.measure[:-1] * np.sin(c31df.angle[:-1]/180*np.pi)
c30x=c30df.measure[:-1] * np.sin(c30df.angle[:-1]/180*np.pi)
c30y=c30df.measure[:-1] * np.sin(c30df.angle[:-1]/180*np.pi)
c31x = np.r_[c31x, c31x[0]]
c31y = np.r_[c31y, c31y[0]]
c30x = np.r_[c30x, c30x[0]]
c30y = np.r_[c30y, c30y[0]]
# noinspection PyTupleAssignmentBalance
c31tck, c31u = interpolate.splprep([c31x, c31y], s=0, per=True)
c31xi, c31yi = interpolate.splev(np.linspace(0,1,1000), c31tck)
# noinspection PyTupleAssignmentBalance
c30tck, c30u = interpolate.splprep([c30x, c30y], s=0, per=True)
c30xi, c30yi = interpolate.splev(np.linspace(0,1,1000), c30tck)
def cart2pol(x,y):
    rho = np.sqrt(x**2+y**2)
    phi = np.arctan2(y,x)
    return(rho, phi)
fig = plt.figure(figsize=(12,8))
c31ax = fig.add_subplot(projection='polar')
c31ax.set_theta_zero_location('N')
c31ax.set_theta_direction(1)
c31ax.set_thetamax(180)
c31ax.plot(cart2pol(c31xi, c31yi)[1], cart2pol(c31xi, c31yi)[0], linewidth=1,      linestyle='solid', color='red', label='Chart')
c30ax = fig.add_subplot(projection='polar')
c30ax.set_theta_zero_location('N')
c30ax.set_theta_direction(-1)
c30ax.set_thetamax(180)
c30ax.plot(cart2pol(c30xi, c30yi)[1], cart2pol(c30xi, c30yi)[0], linewidth=1, linestyle='solid', color='green', label='Chart')
plt.tight_layout()
plt.show()

I have tried moving theta position around, and it changed the graph but still sat in the wrong position.

解决方案

更改此行：

c30x=c30df.measure[:-1] * np.sin(c30df.angle[:-1]/180*np.pi)

对此：

c30x=c30df.measure[:-1] * np.cos(c30df.angle[:-1]/180*np.pi)

当您使用 时add_subplot()，您需要提供预期的布局以及您的子图将适合该布局的位置。其中一种方法是将其称为add_subplot(nrows, nlins, pos).

在您的情况下，您需要一行和两列，因此：

c31ax = fig.add_subplot(1, 2, 1, projection='polar')
c30ax = fig.add_subplot(1, 2, 2, projection='polar')