大约有 16,000 项符合查询结果（耗时：0.0304秒） [XML]
Why does GCC generate such radically different assembly for nearly the same C code?
...is being optimized to this:
int fast_trunc_one(int i) {
int mantissa, exponent;
mantissa = (i & 0x07fffff) | 0x800000;
exponent = 150 - ((i >> 23) & 0xff);
if (exponent < 0) {
return (mantissa << -exponent); /* diff */
} else {
...
Sort rows in data.table in decreasing order on string key `order(-x,v)` gives error on data.table 1.
...d the following answer is no longer necessary.
You can use DT[order(-rank(x), y)].
x y v
1: c 1 7
2: c 3 8
3: c 6 9
4: b 1 1
5: b 3 2
6: b 6 3
7: a 1 4
8: a 3 5
9: a 6 6
share
|
improve this an...
Using std Namespace
...ace std won't enable you to use count instead of std::count.
The classic example of an unwanted name conflict is something like the following. Imagine that you are a beginner and don't know about std::count. Imagine that you are either using something else in <algorithm> or it's been pulled i...
Peak-finding algorithm for Python/SciPy
...rs width, threshold, distance and above all prominence to get a good peak extraction.
According to my tests and the documentation, the concept of prominence is "the useful concept" to keep the good peaks, and discard the noisy peaks.
What is (topographic) prominence? It is "the minimum height nece...
how to check if object already exists in a list
...
It depends on the needs of the specific situation. For example, the dictionary approach would be quite good assuming:
The list is relatively stable (not a lot of inserts/deletions, which dictionaries are not optimized for)
The list is quite large (otherwise the overhead of the di...
Expression Versus Statement
...
Expression: Something which evaluates to a value. Example: 1+2/x
Statement: A line of code which does something. Example: GOTO 100
In the earliest general-purpose programming languages, like FORTRAN, the distinction was cryst...
Can't operator == be applied to generic types in C#?
...an't make that assumption.
However, this will compile because it is more explicit:
bool Compare<T>(T x, T y) where T : class
{
return x == y;
}
Follow up to additional question, "But, in case I'm using a reference type, would the the == operator use the predefined refer...
What is Linux’s native GUI API?
Both Windows (Win32 API) and OS X (Cocoa) have their own APIs to handle windows, events and other OS stuff. I have never really got a clear answer as to what Linux’s equivalent is?
...
best way to preserve numpy arrays on disk
...
would you be willing to provide some example code using these packages to save an array?
– dbliss
Apr 13 '15 at 23:36
12
...
What's the difference between globals(), locals(), and vars()?
... or the dictionary of the argument.
locals and vars could use some more explanation. If locals() is called inside a function, it updates a dict with the values of the current local variable namespace (plus any closure variables) as of that moment and returns it. Multiple calls to locals() in the ...