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How to install both Python 2.x and Python 3.x in Windows
I do most of my programming in Python 3.x on Windows 7, but now I need to use the Python Imaging Library (PIL), ImageMagick, and wxPython, all of which require Python 2.x.
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What is :: (double colon) in Python when subscripting sequences?
I know that I can use something like string[3:4] to get a substring in Python, but what does the 3 mean in somesequence[::3] ?
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[since C++11] std::array的使用 - C/C++ - 清泛网 - 专注C/C++及内核技术
...类、没有虚函数.
因此不支持这样的构造方法：array<int, 3> a({1, 2, 4});
初始化array最常用的方法是使用赋值运算符和初始化列表：
array<int, 3> a = {1, 2, 3};
array<int, 100> b = {1, 2, 3}; // a[0] ~ a[2] = 1, 2, 3; a[3] ~ a[99] = 0, 0, 0 ... 0;
array<in...
Split a vector into chunks in R
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326
A one-liner splitting d into chunks of size 20:
split(d, ceiling(seq_along(d)/20))
More det...
Remove all occurrences of a value from a list?
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23 Answers
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Creating dataframe from a dictionary where entries have different lengths
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134
In Python 3.x:
import pandas as pd
import numpy as np
d = dict( A = np.array([1,2]), B = np.ar...
Lua简明教程 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...行lua命令后进入lua的shell中执行语句。
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chenhao-air:lua chenhao$ lua
Lua 5.2.2 Copyright (C) 1994-2013 Lua.org, PUC-Rio
> print("Hello, World")
Hello, World
>
也可以把脚本存成一个文件，用如下命令...
How to apply a function to two columns of Pandas dataframe
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318
Here's an example using apply on the dataframe, which I am calling with axis = 1.
Note the d...
Index all *except* one item in python
...you could use a list comp. For example, to make b a copy of a without the 3rd element:
a = range(10)[::-1] # [9, 8, 7, 6, 5, 4, 3, 2, 1, 0]
b = [x for i,x in enumerate(a) if i!=3] # [9, 8, 7, 5, 4, 3, 2, 1, 0]
This is very general, and can be used with all iterables, incl...
Filter rows which contain a certain string
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263
The answer to the question was already posted by the @latemail in the comments above. You can us...