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data.table vs dplyr: can one do something well the other can't or does poorly?
...y), as this column exists only in shallow copied DT
DT[x > 2L, x := 3L] ## have to copy (like base R / dplyr does always); otherwise original DT will
## also get modified.
}
By not using shallow(), the old functionality is retained:
bar <- function(D...
How do I check out a remote Git branch?
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34 Answers
34
Active
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OpenSSH升级后不能登录的问题 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...install telnet
详细配置请看
http://jingyan.baidu.com/article/9f63fb91ac7ebcc8400f0e94.html
配置完成后 使用telnet 登录到服务器
开始更新openssh
yum update openssl
yum update openssh
重启服务
service sshd restart
使用ssh –V 查看更...
Is the C# static constructor thread safe?
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193
Static constructors are guaranteed to be run only once per application domain, before any instan...
Rollback to an old Git commit in a public repo
...heckout [revision] .
where [revision] is the commit hash (for example: 12345678901234567890123456789012345678ab).
Don't forget the . at the end, very important. This will apply changes to the whole tree. You should execute this command in the git project root. If you are in any sub directory, th...
【BLE技术内幕】BLE技术揭秘 - 创客硬件开发 - 清泛IT论坛，有思想、有深度
...uetooth SIG）在2010年发布了跨时代的蓝牙4.0，它并不是蓝牙3.0的简单升级版本，而是全新的技术架构，蓝牙4.0版本分两种模式：单模蓝牙和双模蓝牙。常见的蓝牙音箱，是典型的双模蓝牙，它需要传输大量的音频数据。而小米手环...
What is the difference between a static and a non-static initialization code block
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Michael
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answered Dec 2 '08 at 20:35
Lawrence DolLawre...
Why is MATLAB so fast in matrix multiplication?
...uple of times, and then:
>> tic, C = A * A; toc
Elapsed time is 0.075396 seconds.
>> tic, gC = gA * gA; toc
Elapsed time is 0.008621 seconds.
MATLAB uses highly optimized libraries for matrix multiplication which is why the plain MATLAB matrix multiplication is so fast. The gpuArray ve...
How to dynamically change header based on AngularJS partial view?
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342
You could define controller at the <html> level.
<html ng-app="app" ng-controller="...
Difference between \w and \b regular expression meta characters
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edited Feb 4 '15 at 23:58
answered Aug 8 '12 at 23:50
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