哪个更有效？ [英] Which is More Efficient?
问题描述
我有一个程序占用了大量的CPU，并希望尽可能高效地使用它来实现它。那么
中的哪一个会更有效率，知道l是一个列表并且大小是
a数？
l = l [：size]
del l [size：]
如果它有所不同，列表中的所有内容都是可变的。
I have a program that uses up a lot of CPU and want to make it is
efficient as possible with what I have to work with it. So which of the
following would be more efficient, knowing that l is a list and size is
a number?
l=l[:size]
del l[size:]
If it makes a difference, everything in the list is mutable.
推荐答案
测量并找出答案。听起来像是对你的时间的一点投资
学习如何衡量表现可能会给你带来好处。
Measure it and find out. Sounds like a little investment in your time
learning how to measure performance may pay dividends for you.
" Dustan" <都********** @ gmail.com>写道：
"Dustan" <Du**********@gmail.com> writes:
我有一个耗尽了大量CPU的程序，并希望尽可能高效地利用它来处理它。
描述您的程序并找到最慢的精确部件。
最慢。在此之前尝试优化是浪费你的时间。
因此，知道l是列表并且大小是数字，以下哪项会更有效？
l = l [：size]
del l [size：]
I have a program that uses up a lot of CPU and want to make it is
efficient as possible with what I have to work with it.
Profile your program and find the precise parts that are the
slowest. Attempting to optimise before that is a waste of your time.
So which of the following would be more efficient, knowing that l is
a list and size is a number?
l=l[:size]
del l[size:]
当你描述它时，哪一个在你的程序中效率更高
表现？
< URL：http：//docs.python.org/lib/profile.html>
-
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` \，非常字面意思，非常真实我们大脑的很大一部分已经演变成了。（b）b _o__）。 - 道格拉斯亚当斯|
Ben Finney
Which one is more efficient in your program, when you profile its
performance?
<URL:http://docs.python.org/lib/profile.html>
--
\ "Working out the social politics of who you can trust and why |
`\ is, quite literally, what a very large part of our brain has |
_o__) evolved to do." -- Douglas Adams |
Ben Finney
Dustan写道：
Dustan wrote:
I有一个程序，耗尽了大量的CPU，并希望尽可能高效，我必须使用它。那么
以下哪一个会更有效率，知道l是一个列表并且大小是一个数字？
l = l [：size]
del l [size：]
既然你有这个程序，那么测试
两个替代品应该不难吗？
（理论上，del在大多数情况下应该更快，因为它避免了创建另一个对象的
。但唯一可以确定的方法是
来试试吧。
如果它有所不同，列表中的所有内容都是可变的。
I have a program that uses up a lot of CPU and want to make it is
efficient as possible with what I have to work with it. So which of the
following would be more efficient, knowing that l is a list and size is
a number?
l=l[:size]
del l[size:]
since you have the program, it shouldn''t that hard to test the
two alternatives, should it ?
(in theory, del should be faster in most cases, since it avoids
creating another object. but the only way to tell for sure is
to try it out).
If it makes a difference, everything in the list is mutable.
唯一的区别是Python中的可变和不可变对象
是可变对象具有允许您修改对象的方法
内容，而不可变对象没有这样的方法。
< / F>
the only difference between mutable and immutable objects in Python
is that mutable objects have methods that let you modify the object
contents, while immutable objects don''t have such methods.
</F>
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