我需要一个函数,它接受一个列表并输出True,如果输入列表中的所有元素使用标准相等运算符计算彼此相等,否则输出False。

我觉得最好是遍历列表,比较相邻的元素,然后与所有结果布尔值。但我不知道最python的方法是什么。


当前回答

你可以:

reduce(and_, (x==yourList[0] for x in yourList), True)

python让你导入operator.and_这样的操作符是相当烦人的。从python3开始,还需要导入functools.reduce。

(您不应该使用此方法,因为如果它发现不相等的值,它不会中断,而是会继续检查整个列表。这里只是作为完整性的回答。)

其他回答

或者使用numpy的diff方法:

import numpy as np
def allthesame(l):
    return np.unique(l).shape[0]<=1

并呼吁:

print(allthesame([1,1,1]))

输出:

True

检查是否所有元素都等于第一个。

np。allclose(数组,数组[0])

我怀疑这是“最python化的”,但类似于:

>>> falseList = [1,2,3,4]
>>> trueList = [1, 1, 1]
>>> 
>>> def testList(list):
...   for item in list[1:]:
...     if item != list[0]:
...       return False
...   return True
... 
>>> testList(falseList)
False
>>> testList(trueList)
True

会成功的。

最佳答案

Twitter上有一个不错的帖子,介绍了实现all_equal()函数的各种方法。

给定一个列表输入,最好的提交是:

 t.count(t[0]) == len(t)  

其他方法

下面是线程的结果:

Have groupby() compare adjacent entries. This has an early-out for a mismatch, does not use extra memory, and it runs at C speed. g = itertools.groupby(s) next(g, True) and not next(g, False) Compare two slices offset from one another by one position. This uses extra memory but runs at C speed. s[1:] == s[:-1] Iterator version of slice comparison. It runs at C speed and does not use extra memory; however, the eq calls are expensive. all(map(operator.eq, s, itertools.islice(s, 1, None))) Compare the lowest and highest values. This runs at C speed, doesn't use extra memory, but does cost two inequality tests per datum. min(s) == max(s) # s must be non-empty Build a set. This runs at C speed and uses little extra memory but requires hashability and does not have an early-out. len(set(t))==1. At great cost, this handles NaNs and other objects with exotic equality relations. all(itertools.starmap(eq, itertools.product(s, repeat=2))) Pull out the first element and compare all the others to it, stopping at the first mismatch. Only disadvantage is that this doesn't run at C speed. it = iter(s) a = next(it, None) return all(a == b for b in it) Just count the first element. This is fast, simple, elegant. It runs at C speed, requires no additional memory, uses only equality tests, and makes only a single pass over the data. t.count(t[0]) == len(t)

也许我低估了问题的严重性?检查列表中唯一值的长度。

lzt = [1,1,1,1,1,2]

if (len(set(lzt)) > 1):
    uniform = False
elif (len(set(lzt)) == 1):
    uniform = True
elif (not lzt):
    raise ValueError("List empty, get wrecked")