在Python中绘制色彩图会根据绘制的值范围意外更改？

Question

我使用pyplot.imshow使用以下代码显示带有两个最小点的色彩映射表。然而，运行代码，显示黑色的两个最小点但在错误的位置（它们应该在（x1，y1）和（x2，y2））。而且，如果改变t_max，位置也会变化。我做错了什么？

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轴和Y轴。有趣的是，我只是answered another question，发生了这个问题。

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()