大约有 15,000 项符合查询结果（耗时：0.0306秒） [XML]
What is the benefit of using $() instead of backticks in shell scripts?
...ng to figure out if some form of escaping will work on the backticks.
An example, though somewhat contrived:
deps=$(find /dir -name $(ls -1tr 201112[0-9][0-9]*.txt | tail -1l) -print)
which will give you a list of all files in the /dir directory tree which have the same name as the earliest date...
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
...
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]])
...
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;
}
...
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...