python - 类型错误:不支持的操作数类型 - : 'list' 和 'list'

Question

我正在尝试实现朴素高斯并在执行时出现不受支持的操作数类型错误。 输出:

  execfile(filename, namespace)
  File "/media/zax/MYLINUXLIVE/A0N-.py", line 26, in <module>
    print Naive_Gauss([[2,3],[4,5]],[[6],[7]])
  File "/media/zax/MYLINUXLIVE/A0N-.py", line 20, in Naive_Gauss
    b[row] = b[row]-xmult*b[column]
TypeError: unsupported operand type(s) for -: 'list' and 'list'
>>>   

这是代码

def Naive_Gauss(Array,b):
    n = len(Array)

    for column in xrange(n-1):
        for row in xrange(column+1, n):
            xmult = Array[row][column] / Array[column][column]
            Array[row][column] = xmult
            #print Array[row][col]
            for col in xrange(0, n):
                Array[row][col] = Array[row][col] - xmult*Array[column][col]
            b[row] = b[row]-xmult*b[column]


    print Array
    print b

print Naive_Gauss([[2,3],[4,5]],[[6],[7]])

Answer 1

你不能从一个列表中减去一个列表。

>>> [3, 7] - [1, 2]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for -: 'list' and 'list'

简单的方法是使用 numpy :

>>> import numpy as np
>>> np.array([3, 7]) - np.array([1, 2])
array([2, 5])

您也可以使用列表推导式，但需要更改函数中的代码:

>>> [a - b for a, b in zip([3, 7], [1, 2])]
[2, 5]

---

>>> import numpy as np
>>>
>>> def Naive_Gauss(Array,b):
...     n = len(Array)
...     for column in xrange(n-1):
...         for row in xrange(column+1, n):
...             xmult = Array[row][column] / Array[column][column]
...             Array[row][column] = xmult
...             #print Array[row][col]
...             for col in xrange(0, n):
...                 Array[row][col] = Array[row][col] - xmult*Array[column][col]
...             b[row] = b[row]-xmult*b[column]
...     print Array
...     print b
...     return Array, b  # <--- Without this, the function will return `None`.
...
>>> print Naive_Gauss(np.array([[2,3],[4,5]]),
...                   np.array([[6],[7]]))
[[ 2  3]
 [-2 -1]]
[[ 6]
 [-5]]
(array([[ 2,  3],
       [-2, -1]]), array([[ 6],
       [-5]]))