Matplotlib imshow()cmap的对象太多了

Question

我正在尝试创建2D高斯函数的简单imshow()图(matplotlib v.1.2.1):

import matplotlib.pyplot as plt
import numpy as np
from pylab import *

def gaussian(x,y,stdx,stdy):
    return 1.0/(2*np.pi*stdx*stdy) * (np.exp(-0.5*(x**2/stdx**2 + y**2/stdy**2)))

coords = np.linspace(-1,1,100)
X,Y = np.meshgrid(coords,coords)
std_list = np.linspace(1,2,20)
output = [gaussian(X,Y,std_list[i],std_list[i]) for i in range(len(std_list))]

for i in range(len(output)):
    plt.imshow(X,Y,np.array(output[i]),cmap='bone')
    plt.show()

我收到以下错误:

Traceback (most recent call last):
  File "blur.py", line 14, in <module>
    plt.imshow(X,Y,np.array(output[i]),cmap='bone')
TypeError: imshow() got multiple values for keyword argument 'cmap'

事实上,为了确保我没有疯狂,我完全取出了cmap参数,现在我收到以下错误:

Traceback (most recent call last):
  File "blur.py", line 14, in <module>
    plt.imshow(X,Y,np.array(output[i]))
  File "/home/username/anaconda/lib/python2.7/site-packages/matplotlib/pyplot.py", line     2737, in imshow
    imlim=imlim, resample=resample, url=url, **kwargs)
  File "/home/username/anaconda/lib/python2.7/site-packages/matplotlib/axes.py", line 7098, in imshow
    if norm is not None: assert(isinstance(norm, mcolors.Normalize))
AssertionError

我已经确定imshow()的参数都具有相同的形状,所以我不完全确定我做错了什么.这可能是个错误吗？

Answer 1

imshow不拿x,y,z作为输入.(然而pcolor,pcolormesh确实如此).

要么使用pcolormesh(x, y, z),要么使用extentkwarg来表达.

例如

plt.imshow(Z, extent=[X.min(), X.max(), Y.min(), Y.max()],
           cmap='bone')

要么

plt.pcolormesh(X, Y, Z, cmap='bone')

发生的事情是imshow预期的

imshow(X, cmap=None, norm=None, aspect=None, interpolation=None,
         alpha=None, vmin=None, vmax=None, origin=None, extent=None,
         **kwargs)

请注意,第二个参数是cmap,这解释了为什么当你传入一个额外的cmapkwarg 时你得到的错误.

希望这能使事情变得清晰!祝好运!