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What's the fastest way to merge/join data.frames in R?
...bases as well.
library(plyr)
library(data.table)
library(sqldf)
set.seed(123)
N <- 1e5
d1 <- data.frame(x=sample(N,N), y1=rnorm(N))
d2 <- data.frame(x=sample(N,N), y2=rnorm(N))
g1 <- sample(1:1000, N, replace = TRUE)
g2<- sample(1:1000, N, replace = TRUE)
d <- data.frame(d1, g1,...
App Inventor 2 列表的函数式编程 · App Inventor 2 中文网
... 隐私策略和使用条款 技术支持 service@fun123.cn
What can you use Python generator functions for?
I'm starting to learn Python and I've come across generator functions, those that have a yield statement in them. I want to know what types of problems that these functions are really good at solving.
...
vagrant up failed, /dev/vboxnetctl: no such file or directory
...
I'm running macOS High Sierra 10.13.1 and VirtualBox 5.2.2.
This worked for me:
Grant permission to VirtualBox under System Preferences > Security & Privacy > General (this request is new to macOS High Sierra)
Open Terminal and r...
What is “android.R.layout.simple_list_item_1”?
...a reference to an built-in XML layout document that is part of the Android OS, rather than one of your own XML layouts.
Here is a further list of layouts that you can use:
http://developer.android.com/reference/android/R.layout.html
(Updated link thanks @Estel: https://github.com/android/platform_...
npm global path prefix
...houldn't have to do it.
Run this:
npm config get prefix
The default on OS X is /usr/local, which means that npm will symlink binaries into /usr/local/bin, which should already be on your PATH (especially if you're using Homebrew).
So:
npm config set prefix /usr/local if it's something else, a...
Perl build, unit testing, code coverage: A complete working example
...tTestCall3, "false", "argumentTest() IS false test");
# Test argumentTest(123)
my $argumentTestCall4 = HelloPerlBuildWorld::argumentTest(123);
is($argumentTestCall4, "unknown", "argumentTest() IS unknown test");
Now back up in your top level project directory, create a text file named "Build.PL"...
How do I print a list of “Build Settings” in Xcode project?
...mple
PATH "/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin:/Developer/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin"
LANG en_US.US-ASCII
IPHONEOS_DEPLOYMENT_TARGET 4.1
ACTION ...
How can I output a UTF-8 CSV in PHP that Excel will read properly?
...
To quote a Microsoft support engineer,
Excel for Mac does not currently support UTF-8
Update, 2017: This is true of all versions of Microsoft Excel for Mac before Office 2016. Newer versions (from Office 365) do now support UTF-8.
In...
Mock framework vs MS Fakes frameworks
...imilar to this:
Expect.Once.On(mockStudentRepository).Method("Find").With(123);
This is another reason why I'd prefer RhinoMocks and Moq over NMock, NMock uses the older expectation style whereas RhinoMocks and Moq both support the Arrange/Act/Assert approach where you specify you expected intera...