August 2018
Intermediate to advanced
227 pages
4h 16m
Chinese
Content preview from 高效R语言编程
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12
｜
第
1
章
高效
R
编程是高效编程理念在
R
编程中的应用。所有的语言是不同的
,
所以
高效的
R
代码不同于其他语言的高效代码。很多包性能优良，对很多操作来说，
用户仅仅需要选用恰当的包并正确使用它即可获取最大的计算效率。
R
语言
中的很多方案都可获取相同结果，但一些方案的运行效率不高。因此，在学
会编写“快码”之前要先学会不写“慢码”。
回到前言中所提及的关于两辆汽车类比，一些应用案例下高效的
R
编程堪比
将你的老旧、笨重、油耗高
SUV
车更换成轻巧的蹬车。寻求优化性能的过程
将抵消部分高效，所以找到你代码中的瓶颈很关键，发现后加以改善从而获
得计算效率的最大提升。联想到
R
作为灵活性语言的特点，高效
R
编程不仅
仅在计算效率上足够快，并且从编程者角度上看也足够快。毕竟，你与同事
已经做得比较好了，另外工作之外还有很多事待做，快速完成工作并抽空做
一些有乐趣的事也是重要的。
为何需要高效？
计算机的性能一直在提升，这不能替代对高效计算的追求吗？答案很简单：
不能。在大数据时代，停滞不前的计算机主频（见第
8
章）、计算瓶颈比以
往任何时候都妨碍你的工作。高效程序员能“解决更复杂的任务、提出更有
雄心的问题和在自己领域中做更前沿分析”（
Visser et al .2015
）。
下面举例说明效率在至关重要场合中的重要性。
Robin
正在履行的合同，是一
项构建自行车交通的统计，必须在不到
4
个月的时间里部署完毕。为了这个
项目，他在
stplanr
包的基础上开发了 line2route() 函数并通过
CycleStreets
的
API
生成路线。项目本身需要成千上万的路线 ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.