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Pandas groupby: How to get a union of strings
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dtype: object
When you apply your own function, there is not automatic exclusions of non-numeric columns. This is slower, though, than the application of .sum() to the groupby
In [8]: df.groupby('A').apply(lambda x: x.sum())
Out[8]:
A B C
A
1 2 1....
Why doesn't GCC optimize a*a*a*a*a*a to (a*a*a)*(a*a*a)?
...h greatly slows down the performance. (In contrast, Intel C++ Compiler , executable icc , will eliminate the library call for pow(a,6) .)
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How is null + true a string?
...om the C# language spec.
From section 7.3.4:
An operation of the form x op y, where op is an overloadable binary operator, x is an expression of type X, and y is an expression of type Y, is processed as follows:
The set of candidate user-defined operators provided by X and Y for the ope...
How does a ArrayList's contains() method evaluate objects?
...object and add it to my ArrayList . If I then create another object with exactly the same constructor input, will the contains() method evaluate the two objects to be the same? Assume the constructor doesn't do anything funny with the input, and the variables stored in both objects are identical....
NumPy: function for simultaneous max() and min()
numpy.amax() will find the max value in an array, and numpy.amin() does the same for the min value. If I want to find both max and min, I have to call both functions, which requires passing over the (very big) array twice, which seems slow.
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Fastest way to check if a value exists in a list
What is the fastest way to know if a value exists in a list (a list with millions of values in it) and what its index is?
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List OrderBy Alphabetical Order
... looking to quickly sort a Generic List<T> . For the sake of this example, let's say I have a List of a Person type with a property of lastname. How would I sort this List using a lambda expression?
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Awk学习笔记 - 更多技术 - 清泛网 - 专注C/C++及内核技术
Awk学习笔记awk是一种编程语言，用于在linux unix下对文本和数据进行处理。数据可以来自标准输入、一个或多个文件，或其它命令的输出。它支持用户自定义函数和动态正则表达式等先进功能，是linux unix下的一个强大编程工具。
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How to get the client IP address in PHP [duplicate]
...s the most reliable value you can find.
However, they can be behind a proxy server in which case the proxy may have set the $_SERVER['HTTP_X_FORWARDED_FOR'], but this value is easily spoofed. For example, it can be set by someone without a proxy, or the IP can be an internal IP from the LAN behind...