如何在Python中减去两个长列表中特定切片的对应元素?

starmap() 和 dropwhile() :

from itertools import starmap, dropwhile

x = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]
y = [None, None, None, None, None, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100]

# substract corresponding elements
m = starmap(lambda x, y: x - y if y else None, zip(x, y))

# filter None
list(dropwhile(lambda x: not x, m))
# [-4, -13, -22, -31, -40, -49, -58, -67, -76, -85]

试试这个,它会处理两个列表中的“无”。我们不需要手动跟踪它们。如果不需要前5个,我们可以在减法运算上加一个切片。

subtrct=[None if val is None else (val - (0 if y[index] is None else y[index])) for index, val in enumerate(x)]

正如@meowgoesedog在评论中所说,数组索引从0开始。

另外,由于您的两个列表大小相同,您可以压缩它们,以使代码看起来更好,因此这里有一个压缩列表的解决方案:

result = []

for i, j in list(zip(x, y))[5:]:
  result.append(i - j)

result = []

for i in range(x[5:] - 1):
  result.append(x[i] - x[j])

你可以用 enumerate

前任:

x = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15]
y = [None,None,None,None,None,10,20,30,40,50,60,70,80,90,100]

result = []
for i, v in enumerate(x[5:], 5):
    result.append(v - y[i])
print(result)

[-4, -13, -22, -31, -40, -49, -58, -67, -76, -85]

y[15] (因为15是 x[14]

y 只有15个元素,并且由于列表项从索引0开始,因此 list index out of range .

zip 跳过 None

x = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15]

y = [None,None,None,None,None,10,20,30,40,50,60,70,80,90,100]

result = []

for val_x, val_y in zip(x, y):
    if(val_y is None):
        continue
    result.append(val_x - val_y)

print(result)

输出:

[-4, -13, -22, -31, -40, -49, -58, -67, -76, -85]

或者作为列表理解:

result = [ (val_x - val_y) for val_x, val_y in zip(x, y) if (val_y is not None) ]

你应该这样做:

for val1, val2 in zip(x[5:], y[5:]):
    result.append(val1 - val2)

for val1, val2 in list(zip(x, y))[5:]:
    result.append(val1 - val2)

你也可以跳过 None 价值观,比如:

for val1, val2 in zip(x, y):
    if val2 is not None:  # can also check if val1 is not None if needed
        result.append(val1 - val2)

IndexError 是那个 i 在你的循环中被赋值(不是索引!)的 x i = 15 当该元素的索引仅为 14 .