大约有 47,000 项符合查询结果（耗时：0.0475秒） [XML]
Is std::vector so much slower than plain arrays?
...ds
UseVector completed in 4.412 seconds
UseVectorPushBack completed in 8.017 seconds
The whole thing completed in 14.626 seconds
So array is twice as quick as vector.
But after looking at the code in more detail this is expected; as you run across the vector twice and the array only once...
Add column with constant value to pandas dataframe [duplicate]
...with partially aligned indices:
In [7]: from pandas import DataFrame
In [8]: from numpy.random import randint
In [9]: df = DataFrame({'a': randint(3, size=10)})
In [10]:
In [10]: df
Out[10]:
a
0 0
1 2
2 0
3 1
4 0
5 0
6 0
7 0
8 0
9 0
In [11]: s = df.a[:5]
In [12]: dfa, sa = df.ali...
Why do enum permissions often have 0, 1, 2, 4 values?
Why are people always using enum values like 0, 1, 2, 4, 8 and not 0, 1, 2, 3, 4 ?
7 Answers
...
Change UICollectionViewCell size on different device orientations
...
followbenfollowben
8,45644 gold badges3434 silver badges3838 bronze badges
...
Is MATLAB OOP slow or am I doing something wrong?
... 0.02261 sec 0.23 usec per call
nop1-5() functions: 0.02182 sec 0.22 usec per call
nop() subfunction: 0.02244 sec 0.22 usec per call
@()[] anonymous function: 0.08461 sec 0.85 usec per call
nop(obj) method: 0.24664 sec 2.47 usec per call
no...
How to get the index of a maximum element in a numpy array along one axis
...iroeumiro
165k2626 gold badges267267 silver badges248248 bronze badges
1
...
Change a column type from Date to DateTime during ROR migration
...
answered Mar 4 '11 at 8:42
apneadivingapneadiving
109k2525 gold badges207207 silver badges207207 bronze badges
...
How to get the last N rows of a pandas DataFrame?
...
408
Don't forget DataFrame.tail! e.g. df1.tail(10)
...
Ask for User Permission to Receive UILocalNotifications in iOS 8
...
Since iOS 8 you need to ask user's permission to show notifications from your app, this applies for both remote/push and local notifications. In Swift you can do it like this,
Update for Swift 2.0
func application(application: UIAppl...