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How do I replace NA values with zeros in an R dataframe?
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See my comment in @gsk3 answer. A simple example:
> m <- matrix(sample(c(NA, 1:10), 100, replace = TRUE), 10)
> d <- as.data.frame(m)
V1 V2 V3 V4 V5 V6 V7 V8 V9 V10
1 4 3 NA 3 7 6 6 10 6 5
2 9 8 9 5 10 NA 2 1 7 ...
ActiveRecord, has_many :through, and Polymorphic Associations
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3 Answers
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Java lib or app to convert CSV to XML file? [closed]
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edited Feb 7 '13 at 10:36
CloudyMarble
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Is there a decorator to simply cache function return values?
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Starting from Python 3.2 there is a built-in decorator:
@functools.lru_cache(maxsize=100, typed=False)
Decorator to wrap a function with a memoizing callable that saves up to the maxsize most recent calls. It can save time when an expensive or...
Split list into multiple lists with fixed number of elements
...an iterator, but you can convert the result to a list,
scala> List(1,2,3,4,5,6,"seven").grouped(4).toList
res0: List[List[Any]] = List(List(1, 2, 3, 4), List(5, 6, seven))
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Swift 编程语言入门教程 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...教程，分享给大家
原文地址：http://gashero.iteye.com/blog/2075324
目录
1 简介
2 Swift入门
3 简单值
4 控制流
5 函数与闭包
6 对象与类
7 枚举与结构
1 简介
今天凌晨Apple刚刚发布了Swift编程语言，本文从其发布...
How to get execution time in rails console?
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3 Answers
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Convert a PHP object to an associative array
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32 Answers
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iPhone Simulator location
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Simulator: ~/Library/Application Support/iPhone Simulator/
You can browse simulator files from ...
Finding the index of elements based on a condition using python list comprehension
... of a list.
>>> import numpy
>>> a = numpy.array([1, 2, 3, 1, 2, 3])
>>> a
array([1, 2, 3, 1, 2, 3])
>>> numpy.where(a > 2)
(array([2, 5]),)
>>> a > 2
array([False, False, True, False, False, True], dtype=bool)
>>> a[numpy.where(a > 2...