根據繪製的值的範圍，在Python中繪製顏色映射會意外改變？

Question

我正在使用pyplot.imshow以下面的代碼顯示帶有兩個最小點的顏色映射。然而，運行代碼顯示了黑色的兩個最小點，但是位置錯誤（它們應該在（x1，y1）和（x2，y2））。更重要的是，如果改變t_max，位置也會有所不同。我究竟做錯了什麼？

import numpy 
import matplotlib.pyplot as pyplot 
import matplotlib.cm as cm 

a = 0.1 
b = 4 
X = 1.1*10**7 
x1, y1 = 36, 48*numpy.pi/32 
x2, y2 = 49, 57*numpy.pi/32 
d1 = (-101872 + X - (X - 2122) * (1+(a*(x1-x2)**2 + (b*(y1-y2))**2)))/((1/(1+(a*(x2-x1)**2 + (b*(y2-y1))**2))) - (1+(a*(x1-x2)**2 + (b*(y1-y2))**2))) 
d2 = (X - d1 - 2122)*(1+(a*(x1-x2)**2 + (b*(y1-y2))**2)) 
def E_density(x, y): 
    return X - d1/(1+(a*(x-x1)**2 + (b*(y-y1))**2)) - d2/(1+(a*(x-x2)**2 + (b*(y-y2))**2)) 

t_min, t_max = 14, 104 
phi_min, phi_max = 47*numpy.pi/32, 61*numpy.pi/32 
dt = 1 
dphi = numpy.pi/128 
x_axis = numpy.arange(t_min, t_max, dt) 
y_axis = numpy.arange(phi_min, phi_max, dphi) 

f = numpy.zeros((len(x_axis), len(y_axis))) 
for ix, x in enumerate(x_axis): 
    for iy, y in enumerate(y_axis): 
     f[ix, iy] = E_density(x, y) 

fig1 = pyplot.figure() 
im = pyplot.imshow(f, extent = (t_min, t_max, phi_min, phi_max), origin = 'lower', cmap = cm.gray, aspect = 'auto', vmin = 0, vmax = 10**7) 
pyplot.colorbar(im, orientation = 'vertical') 

pyplot.show() 

Answer 1

您混合了X軸和Y軸。有趣的是我只是answered another question，發生這個問題。

import numpy 
import matplotlib.pyplot as pyplot 
import matplotlib.cm as cm 

a = 0.1 
b = 4 
X = 1.1*10**7 
x1, y1 = 36, 48*numpy.pi/32 
x2, y2 = 49, 57*numpy.pi/32 
d1 = (-101872 + X - (X - 2122) * (1+(a*(x1-x2)**2 + (b*(y1-y2))**2)))/((1/(1+(a*(x2-x1)**2 + (b*(y2-y1))**2))) - (1+(a*(x1-x2)**2 + (b*(y1-y2))**2))) 
d2 = (X - d1 - 2122)*(1+(a*(x1-x2)**2 + (b*(y1-y2))**2)) 
def E_density(x, y): 
    return X - d1/(1+(a*(x-x1)**2 + (b*(y-y1))**2)) - d2/(1+(a*(x-x2)**2 + (b*(y-y2))**2)) 

t_min, t_max = 14, 104 
phi_min, phi_max = 47*numpy.pi/32, 61*numpy.pi/32 
dt = 1 
dphi = numpy.pi/128 
x_axis = numpy.arange(t_min, t_max, dt) 
y_axis = numpy.arange(phi_min, phi_max, dphi) 

f = numpy.zeros((len(y_axis), len(x_axis))) 
for ix, x in enumerate(x_axis): 
    for iy, y in enumerate(y_axis): 
     f[iy,ix] = E_density(x, y) 

fig1 = pyplot.figure() 
im = pyplot.imshow(f, extent = (t_min, t_max, phi_min, phi_max), origin = 'lower', cmap = cm.gray, aspect = 'auto', vmin = 0, vmax = 10**7) 
pyplot.colorbar(im, orientation = 'vertical') 

pyplot.show()