Python：在元组列表中查找最小值、最大值
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Python: Find the min, max value in a list of tuples
提问by user483144
alist = [(1,3),(2,5),(2,4),(7,5)]
I need to get the min max value for each position in tuple.
我需要获取元组中每个位置的最小最大值。
Fox example: The exepected output of alist is
Fox 示例：alist 的预期输出为
min_x = 1
max_x = 7
min_y = 3
max_y = 5
Is there any easy way to do?
有什么简单的方法吗？
回答by cobbal
map(max, zip(*alist))
This first unzips your list, then finds the max for each tuple position
这首先解压缩您的列表，然后找到每个元组位置的最大值
>>> alist = [(1,3),(2,5),(2,4),(7,5)]
>>> zip(*alist)
[(1, 2, 2, 7), (3, 5, 4, 5)]
>>> map(max, zip(*alist))
[7, 5]
>>> map(min, zip(*alist))
[1, 3]
This will also work for tuples of any length in a list.
这也适用于列表中任何长度的元组。
回答by John La Rooy
>>> from operator import itemgetter
>>> alist = [(1,3),(2,5),(2,4),(7,5)]
>>> min(alist)[0], max(alist)[0]
(1, 7)
>>> min(alist, key=itemgetter(1))[1], max(alist, key=itemgetter(1))[1]
(3, 5)
回答by martineau
A generalized approach would be something like this:
一个通用的方法是这样的：
alist = [(1,6),(2,5),(2,4),(7,5)]
temp = map(sorted, zip(*alist))
min_x, max_x, min_y, max_y = temp[0][0], temp[0][-1], temp[1][0], temp[1][-1]
For Python 3, you'd need change the line that createstempto:
对于 Python 3，您需要将创建的行更改temp为：
temp = tuple(map(sorted, zip(*alist)))
The idea can be abstracted into a function which works in both Python 2 and 3:
这个想法可以抽象为一个在 Python 2 和 3 中都可以工作的函数：
from __future__ import print_function
try:
from functools import reduce # moved into functools in release 2.6
except ImportError:
pass
# readable version
def minmaxes(seq):
pairs = tuple()
for s in map(sorted, zip(*seq)):
pairs += (s[0], s[-1])
return pairs
# functional version
def minmaxes(seq):
return reduce(tuple.__add__, ((s[0], s[-1]) for s in map(sorted, zip(*seq))))
alist = [(1,6), (2,5), (2,4), (7,5)]
min_x, max_x, min_y, max_y = minmaxes(alist)
print(' '.join(['{},{}']*2).format(*minmaxes(alist))) # 1,7 4,6
triplets = [(1,6,6), (2,5,3), (2,4,9), (7,5,6)]
min_x, max_x, min_y, max_y, min_z, max_z = minmaxes(triplets)
print(' '.join(['{},{}']*3).format(*minmaxes(triplets))) # 1,7 4,6 3,9
回答by tiwo
At least with Python 2.7, the "zip" is not necessary, so this simplifies to map(max, *data)(where datais an iterator over tuples or lists of the same length).
至少在Python 2.7 中，“zip”不是必需的，因此这简化为map(max, *data)（ where datais an iterator over tuples or lists of the same length）。
回答by toppare
Another solution using enumerate and list comprehension
使用枚举和列表理解的另一种解决方案
alist = [(1,3),(2,5),(2,4),(7,5)]
for num, k in enumerate(['X', 'Y']):
print 'max_%s' %k, max([i[num] for i in alist])
print 'min_%s' %k, min([i[num] for i in alist])
回答by Leo103
For python 3:
对于蟒蛇 3：
alist = [(1,3),(2,5),(2,4),(7,5)]
[x_range, y_range] = list(zip(map(min, *test_list), map(max, *alist)))
print(x_range, y_range) #prints: (1, 7) (3, 5)
Since zip/map returns an iterator <object at 0x00>you need to use list()
由于 zip/map 返回一个迭代器，<object at 0x00>您需要使用list()
