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pandas GroupBy columns with NaN (missing) values
...n the Missing Data section of the docs:
NA groups in GroupBy are automatically excluded. This behavior is consistent with R, for example.
One workaround is to use a placeholder before doing the groupby (e.g. -1):
In [11]: df.fillna(-1)
Out[11]:
a b
0 1 4
1 2 -1
2 3 6
In [12]: df.fil...
Concatenate two slices in Go
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Is this at all performant when the slices are quite big? Or does the compiler not really pass all the elements as parameters?
– Toad
Sep 24 '14 at 8:57
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Is “inline” without “static” or “extern” ever useful in C99?
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Actually this excellent answer also answers your question, I think:
What does extern inline do?
The idea is that "inline" can be used in a header file, and then "extern inline" in a .c file. "extern inline" is just how you ins...
How do I find where JDK is installed on my windows machine?
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Actually, the form %VAR_NAME% is Windows
– sblundy
Jan 13 '11 at 14:29
2
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Creating instance of type without default constructor in C# using reflection
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I originally posted this answer here, but here is a reprint since this isn't the exact same question but has the same answer:
FormatterServices.GetUninitializedObject() will create an instance without calling a constructor. I found...
node.js equivalent of python's if __name__ == '__main__' [duplicate]
I'd like to check if my module is being included or run directly. How can I do this in node.js?
2 Answers
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MFC CSplitterWnd的用法详解 - C/C++ - 清泛网 - 专注C/C++及内核技术
...rWnd类的Create或CreateStatic（）函数；
例子：
CSplitterWnd m_wndSplitter;
BOOL CChildFrame::OnCreateClient( LPCREATESTRUCT lpcs,
CCreateContext* pContext)
{
BOOL bCreateSpltr = m_wndSplitter.CreateStatic( this, 2, 1);
// COneView and CAnotherView are use...
__declspec(dllexport) 导出符号解决链接失败问题 - C/C++ - 清泛网 - 专注C/C++及内核技术
__declspec(dllexport) 导出符号解决链接失败问题特别注意：dllexport、dllimport导出、导入的方式仅针对dll动态库，而lib静态库无需任何申明，宏全部替换成空即可。error LNK2019: 无法解析的外部符号 "public: __thiscall CBtt::CBtt(void)" (??0CBtt@@Q...
Get keys from HashMap in Java
...HashMap contains more than one key. You can use keySet() to get the set of all keys.
team1.put("foo", 1);
team1.put("bar", 2);
will store 1 with key "foo" and 2 with key "bar". To iterate over all the keys:
for ( String key : team1.keySet() ) {
System.out.println( key );
}
will print "foo"...
Passing an integer by reference in Python
...d you can't just assign the "variable" a new value because then you're actually creating a new object (which is distinct from the old one) and giving it the name that the old object had in the local namespace.
Usually the workaround is to simply return the object that you want:
def multiply_by_2(x...