比较列表元素
比较列表元素
提问于 2011-05-29 08:48:45
如何将一个元素与排序列表中的下一个元素进行比较，并打印出它们之间的差异。任何帮助都将不胜感激。
Eg:
lst = [3.18,10.57,14.95,...]
10.57 - 3.18 = 7.39
14.95 - 10.57 = 4.38
...回答 5
Stack Overflow用户
回答已采纳
发布于 2011-05-29 08:54:35
如果您正在操作数值数据，请考虑使用numpy
import numpy as np
lst = [3.18,10.57,14.95]
arr = np.array(lst)
diff = np.diff(arr)
>>> diff
array([ 7.39, 4.38])如果有必要，您可以将其转换回list：
diff_list = list(diff)否则，您可以迭代它，就像迭代列表一样：
for item in diff:
print(item)
7.39
4.38编辑：我计时的五个解决方案非常接近，所以选择一个更容易阅读的解决方案
t = timeit.Timer("[b - a for a, b in zip(l, l[1:])]", "l = range(int(1e6))")
print(t.timeit(1))
>>> 0.523894071579
t = timeit.Timer("list(np.diff(np.array(l)))", "import numpy as np; l = range(int(1e6))")
print(t.timeit(1))
>>> 0.484916915894
t = timeit.Timer("diffs = [l[x + 1] - l[x] for x in range(len(l) - 1)]", "l = range(int(1e6))")
print(t.timeit(1))
>>> 0.363043069839
t = timeit.Timer("[(x, y, y - x) for (x, y) in itertools.izip(l, it)]", "l = range(int(1e6)); it = iter(l); it.next()")
print(t.timeit(1))
>>> 0.54354596138
# pairwise solution
t = timeit.Timer("a, b = itertools.tee(l); next(b, None); [(x, y) for x, y in itertools.izip(a, b)]", "l = range(int(1e6));")
print(t.timeit(1))
>>> 0.477301120758Stack Overflow用户
发布于 2011-05-29 08:52:46
it = iter(lst)
it.next()
print [(x, y, y - x) for (x, y) in itertools.izip(lst, it)]Stack Overflow用户
发布于 2011-05-29 09:00:44
你需要来自itertools的pairwise() recipe，很多Python的优点都来自于它。
>>> for x,y in pairwise(lst):
... print(y, " - ", x, " = ", y - x)
...
10.57 - 3.18 = 7.390000000000001
14.95 - 10.57 = 4.379999999999999页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/6165277
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