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What is “:-!!” in C code?
...ld.
The macro is somewhat misnamed; it should be something more like BUILD_BUG_OR_ZERO, rather than ...ON_ZERO. (There have been occasional discussions about whether this is a confusing name.)
You should read the expression like this:
sizeof(struct { int: -!!(e); }))
(e): Compute expression e....
pandas dataframe columns scaling with sklearn
...ndas dataframe with mixed type columns, and I'd like to apply sklearn's min_max_scaler to some of the columns. Ideally, I'd like to do these transformations in place, but haven't figured out a way to do that yet. I've written the following code that works:
...
How do I execute inserts and updates in an Alembic upgrade script?
... other forms.
Note that Alembic provides some basic data functions: op.bulk_insert() and op.execute(). If the operations are fairly minimal, use those. If the migration requires relationships or other complex interactions, I prefer to use the full power of models and sessions as described below.
T...
How to convert An NSInteger to an int?
...endently of whether you are building for a 32-bit or a 64-bit system.
#if __LP64__ || TARGET_OS_EMBEDDED || TARGET_OS_IPHONE || TARGET_OS_WIN32 || NS_BUILD_32_LIKE_64
typedef long NSInteger;
#else
typedef int NSInteger;
#endif
You can use NSInteger any place you use an int without converting it....
Is there a math nCr function in python? [duplicate]
...
def nCr(n,r):
f = math.factorial
return f(n) / f(r) / f(n-r)
if __name__ == '__main__':
print nCr(4,2)
In Python 3, use the integer division // instead of / to avoid overflows:
return f(n) // f(r) // f(n-r)
Output
6
...
MFC 获取当前时间的几种方法总结 - C/C++ - 清泛网 - 专注C/C++及内核技术
...ime curTime = CTime::GetCurrentTime();CString strCurTime;strCurTime.Format(_T("d d d d:d:d"), curTime...1.CTime类获取当前时间
CTime curTime = CTime::GetCurrentTime();
CString strCurTime;
strCurTime.Format(_T("d/d/d d:d:d"), curTime.GetYear(), curTime.GetMonth(), curTime.GetDay(), curTi...
Google breakpad stackwalker无法加载符号 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...Google breakpad安装好以后，按要求生成 sym，但是最终minidump_stackwalk打印出来的堆栈还是提示找不到符号。这是因为它要求符号文件有一 Google breakpad安装好以后，按要求生成.sym，但是最终 minidump_stackwalk 打印出来的堆栈还是提示...
Print current call stack from a method in Python code
...port traceback
def f():
g()
def g():
for line in traceback.format_stack():
print(line.strip())
f()
# Prints:
# File "so-stack.py", line 10, in <module>
# f()
# File "so-stack.py", line 4, in f
# g()
# File "so-stack.py", line 7, in g
# for line in traceback.form...
How to convert CFStringRef to NSString?
...e using ARC, the new casting syntax is as follows:
NSString *aNSString = (__bridge NSString *)aCFString;
works as well. The key thing to note is that CoreFoundation will often return objects with +1 reference counts, meaning that they need to be released (all CF[Type]Create format functions do th...
How do I get indices of N maximum values in a NumPy array?
...t;> a = [1, 3, 2, 4, 5]
>>> heapq.nlargest(3, range(len(a)), a.__getitem__)
[4, 3, 1]
If you use Python 2, use xrange instead of range.
Source: heapq — Heap queue algorithm
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