最简单的方法是将两个维度相加？ （蟒蛇）

Question

我在总结两个方面需要帮助。

让我说[[0,1,2]，[3,4,5]]作为我的维度，将这些数字相加将返回第15行。

   def sum_dimensions(x):
       x = []
       answer = sum(x)
       return int(x)

赞赏我在代码中指出我的错误。

Answer 1

让我们了解一下。我在我的机器上使用了以下数据集：

data = list(list(range(100000)) for i in range(1000))

我有以下结果：

In [13]: %%timeit                                             
sum(sum(ele) for ele in data)
   ....: 
1 loops, best of 3: 1.15 s per loop

In [14]: %%timeit                                             
sum([sum([item for item in ele]) for ele in data])
   ....: 
1 loops, best of 3: 3.78 s per loop


In [15]: %%timeit                                             
sum(j for i in data for j in i)
   ....: 
1 loops, best of 3: 4.92 s per loop

In [16]: %%timeit                                             
sum(itertools.chain.from_iterable(data))
   ....: 
1 loops, best of 3: 1.61 s per loop

In [18]: %%timeit
sum(map(sum, data))
   ....: 
1 loops, best of 3: 1.16 s per loop

但是对于小数据集，itertools变体比sum(sum变体快2倍。 sum(map(sum似乎完全映射到sum(sum(ele) for ele in data)构造

Answer 2

这就是你要找的东西：

data = [[0,1,2],[3,4,5]]
sum([sum([item for item in ele]) for ele in data])
15

正如@filmor所指出的，这可以简化为：

data = [[0,1,2],[3,4,5]]
sum([sum(ele) for ele in data])
15

至于您的代码，如果您将[[0,1,2],[3,4,5]]作为x传递给函数：

answer = sum(x)

会抛出TypeError。以下

return int(x)

也没有意义。使代码工作的方法是：

def sum_dimensions(x):
   answer = sum(x)
   return answer

data = [[0,1,2],[3,4,5]]
total_sum = 0
for sub_list in data:
    total_sum += sum_dimensions(sub_list)

Answer 3

这是Python，而不是C.

ar = [[0,1,2],[3,4,5]]
result = sum ( [sum(block) for block in ar] )

Answer 4

如果您正在进行其他线性代数，则可能值得考虑numpy：

import numpy as np

x = np.array( [[0,1,2],[3,4,5]] )
print np.sum(x)

Answer 5

试试这个，

>>>sum([sum(i) for i in [[0,1,2],[3,4,5]]])

输出：

15

Answer 6

你可以试试这个：

>>> l = [[0,1,2],[3,4,5]]
>>> 
>>> sum(a for v in l for a in v)
15

Answer 7

也可以使用map()和sum()完成：

a = [[0,1,2],[3,4,5]]
sum(map(sum, a)) #15