ValueError：零大小数组到减少操作最小值，没有identity-Python

Question

我正在尝试计算卫星图像的欧氏距离。我的代码适用于小图像，但对于大图像，它是失败的。我收到错误，无法解决。 错误：

Traceback (most recent call last):
  File "U:\Annoop_WC\Multiband Spectral Anaysis.py", line 139, in <module>
  main()
  File "U:\Annoop_WC\Multiband Spectral Anaysis.py", line 72, in main
  min = np.amin(np.array(ngbh_matrix)[ngbh_matrix != np.amin(ngbh_matrix)])
  File "C:\Python27\ArcGIS10.2\lib\site-packages\numpy\core\fromnumeric.py", line 2354, in amin out=out, keepdims=keepdims)
  File "C:\Python27\ArcGIS10.2\lib\site-packages\numpy\core\_methods.py",line 14, in _amin
out=out, keepdims=keepdims)
 ValueError: zero-size array to reduction operation minimum which has no identity

代码段：

            if np.amin(ngbh_matrix) == noDataValue:
                min = np.amin(np.array(ngbh_matrix)[ngbh_matrix != np.amin(ngbh_matrix)])
            else:
                min = np.amin(ngbh_matrix)
            if (np.amax(ngbh_matrix)) == noDataValue:
                max = np.amax(np.array(ngbh_matrix)[ngbh_matrix != np.amax(ngbh_matrix)])
            else:
                max = np.amax(ngbh_matrix)

关于代码的小描述：我正在将图像读入arcpy并将其转换为numpy数组。然后填充以便与nodatavalue形成邻域。如下Nodatavalue = 0。所以我必须找到邻域矩阵的min，它不等于0。

a= |1 2 3 |
   |4 5 6 |
   |7 8 9 |
 neighborhood matrix = |0 0 0|
                       |0 1 2|
                       |0 4 5|

请帮助解决错误。