Python 在列表列表中查找索引 1 和 2 的最大值

Question

在列表中

[
[[ 979, 2136, 3427, 2221]],

 [[1497,  697, 2843,  721]],

 [[2778, 2194, 3903, 2233]],
]

如此迭代

for line in lines:
    for x1, y1, x2, y2 in line:

我想找到（x1 或 x2 以最大值為准）和（y1 y2 以最大值為准）的最大值

Answer 1

你可以這樣做：

[*map(lambda x: list(map(max, [x[0][:2], x[0][2:]])), mylist)]

[[2136, 3427], [1497, 2843], [2778, 3903]]

Answer 2

import sys
max_x, max_y = [-sys.maxsize,-sys.maxsize]
lines = [
          [[979,2136,3427,2221]],
    
          [[1497,697,2843,721]],
            
          [[2778,2194,3903,2233]]
]
for line in lines:
     for x1, y1, x2, y2 in line:
         if max(x1,x2) > max_x:
             max_x = max(x1,x2)
         if max(y1,y2) > max_y:
             max_y = max(y1,y2)

如果您的點只有正值，您可以將 max_x 和 max_y 初始化為 0。

Answer 3

我更喜歡 Nicolas 的答案的更詳細（但我認為也更易讀）的版本，它保留了for循環並使用命名元組來獲得更有意義的 output：

from collections import namedtuple

Coordinate = namedtuple('Coordinate', ['x', 'y'])

lines = [[[ 979, 2136, 3427, 2221]], [[1497,  697, 2843,  721]], [[2778, 2194, 3903, 2233]]]

maximums = []

for line in lines:
    for x1, y1, x2, y2 in line:
        maximums.append(Coordinate(x=max(x1, x2), y=max(y1, y2)))

print(maximums)
# prints [Coordinate(x=3427, y=2221), Coordinate(x=2843, y=721), Coordinate(x=3903, y=2233)]
print([Coordinate(x=3427, y=2221), Coordinate(x=2843, y=721), Coordinate(x=3903, y=2233)])
# prints [(3427, 2221), (2843, 721), (3903, 2233)]

Answer 4

以下是如何找到每組的最大值：

ls1 = [[[ 979, 2136, 3427, 2221]],
       [[1497,  697, 2843,  721]],
       [[2778, 2194, 3903, 2233]]]

ls2 = [[max(a[0][:2]),
        max(a[0][2:])]
       for a in ls1]

print(ls2)

Output：

[[2136, 3427],
 [1497, 2843],
 [2778, 3903]]

---

---

要找到所有x和y的最大值：

ls1 = [[[ 979, 2136, 3427, 2221]],
       [[1497,  697, 2843,  721]],
       [[2778, 2194, 3903, 2233]]]

x = max([i for j in [a[0][:2] for a in ls1] for i in j])
y = max([i for j in [a[0][2:] for a in ls1] for i in j])

print(x, y)

Output：

2778 3903