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Selecting multiple columns in a pandas dataframe
I have data in different columns but I don't know how to extract it to save it in another variable.
18 Answers
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What is the difference between static_cast and C style casting?
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C++ style casts are checked by the compiler. C style casts aren't and can fail at runtime.
Also, c++ style casts can be searched for easily, whereas it's really hard to search for c style casts.
Another big benefit is that the 4 different C++ style c...
What's the purpose of using braces (i.e. {}) for a single-line if or loop?
...= 0)
j++;
i++;
Oh no! Coming from Python, this looks ok, but in fact it isn't, as it's equivalent to:
int j = 0;
for (int i = 0 ; i < 100 ; ++i)
if (i % 2 == 0)
j++;
i++;
Of course, this is a silly mistake, but one that even an experienced programmer could make.
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计算统计特征（正态分布）函数及实例 - C/C++ - 清泛网 - 专注C/C++及内核技术
...dev_info;
stdev_info.init();
stdev_info.caculate_stdev_info(map_test.begin(), map_test.end(),
[](const std::pair<int, int> &pr) { return pr.second; });
//if (value > stdev_info._ave * 2) { ... }
return 0;
}
stdev.h
#ifndef _UTILITY_STDEV_H_
#define _UTILITY_STDEV_H_
/*
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Memcached下一站：HandlerSocket！ - 更多技术 - 清泛网 - 专注C/C++及内核技术
...过期的数据，就会造成数据不一致。这在强调即时性的Web2.0时代，不可取。
Memcached崩溃后的雪崩效应：作为缓存的Memcached一旦崩溃，MySQL很可能在短时间内承受高负载而宕机。据说前段时间新浪微博就遭遇了这样的问题。
注...
Parse JSON String into a Particular Object Prototype in JavaScript
I know how to parse a JSON String and turn it into a JavaScript Object.
You can use JSON.parse() in modern browsers (and IE9+).
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Set TextView text from html-formatted string resource in XML
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Just in case anybody finds this, there's a nicer alternative that's not documented (I tripped over it after searching for hours, and finally found it in the bug list for the Android SDK itself). You CAN include raw HTML in strings.xml, as lo...
Convert a Scala list to a tuple?
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You can't do this in a typesafe way. Why? Because in general we can't know the length of a list until runtime. But the "length" of a tuple must be encoded in its type, and hence known at compile time. For example, (1,'a',true) has the type (Int, Char, Boolean), which...
Remove grid, background color, and top and right borders from ggplot2
I would like to reproduce the plot immediately below by using ggplot2. I can come close, but cannot remove the top and right borders. Below I present several attempts using ggplot2, including several suggestions found on or via Stackoverflow. Unfortunately I have not been able to get those sugges...
Regular Expressions and negating a whole character group [duplicate]
I'm attempting something which I feel should be fairly obvious to me but it's not. I'm trying to match a string which does NOT contain a specific sequence of characters. I've tried using [^ab] , [^(ab)] , etc. to match strings containing no 'a's or 'b's, or only 'a's or only 'b's or 'ba' but not...