大约有 15,000 项符合查询结果（耗时：0.0338秒） [XML]
Create an empty list in python with certain size
...None, None, None, None, None, None, None, None]
Assigning a value to an existing element of the above list:
>>> l[1] = 5
>>> l
[None, 5, None, None, None, None, None, None, None, None]
Keep in mind that something like l[15] = 5 would still fail, as our list has only 10 element...
Which method performs better: .Any() vs .Count() > 0?
in the System.Linq namespace, we can now extend our IEnumerable's to have the Any() and Count() extension methods .
...
How do I return multiple values from a function? [closed]
...re added in 2.6 for this purpose. Also see os.stat for a similar builtin example.
>>> import collections
>>> Point = collections.namedtuple('Point', ['x', 'y'])
>>> p = Point(1, y=2)
>>> p.x, p.y
1 2
>>> p[0], p[1]
1 2
In recent versions of Python 3 (...
What are paramorphisms?
...
foldr :: (a -> b -> b) -> b -> [a] -> b
para c n (x : xs) = c x xs (para c n xs)
foldr c n (x : xs) = c x (foldr c n xs)
para c n [] = n
foldr c n [] = n
Some people call paramorphisms "primitive recursion" by contrast with catamorphisms (foldr) being "iter...
Xml Namespace breaking my xpath! [duplicate]
I have the following XML:
5 Answers
5
...
What is the difference between Python's list methods append and extend?
What's the difference between the list methods append() and extend() ?
20 Answers
2...
How does java do modulus calculations with negative numbers?
... get a negative number for negative inputs then you can use this:
int r = x % n;
if (r > 0 && x < 0)
{
r -= n;
}
Likewise if you were using a language that returns a negative number on a negative input and you would prefer positive:
int r = x % n;
if (r < 0)
{
r += n;
}
...
How to convert 2D float numpy array to 2D int numpy array?
...
Use the astype method.
>>> x = np.array([[1.0, 2.3], [1.3, 2.9]])
>>> x
array([[ 1. , 2.3],
[ 1.3, 2.9]])
>>> x.astype(int)
array([[1, 2],
[1, 2]])
...
Installing PG gem on OS X - failure to build native extension
...
Same error for me and I didn't experience it until I downloaded OS X 10.9 (Mavericks). Sigh, another OS upgrade headache.
Here's how I fixed it (with homebrew):
Install another build of Xcode Tools (typing brew update in the terminal will prompt you to u...
Why are there two kinds of functions in Elixir?
I'm learning Elixir and wonder why it has two types of function definitions:
8 Answers
...