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data.table vs dplyr: can one do something well the other can't or does poorly?
... ## data.table syntax
left_join(DT2, DT1) ## dplyr syntax
# 2. select columns while join
DT1[DT2, .(z, i.mul)]
left_join(select(DT2, x, y, mul), select(DT1, x, y, z))
# 3. aggregate while join
DT1[DT2, .(sum(z) * i.mul), by = .EACHI]
DF1 %>% group_by(x, y) %>% summarise(z = su...
How do I simulate a hover with a touch in touch enabled browsers?
...for added usefulness, add this to your CSS as well:
.hover {
-webkit-user-select: none;
-webkit-touch-callout: none;
}
To stop the browser asking you to copy/save/select the image or whatever.
Easy!
share
...
图片处理使用指导 · App Inventor 2 中文网
...器1.AfterPicking() {
小图 = 图片处理1.Compress(图像选择器1.Selection, 1080, 80)
图像1.Picture = 小图
标签_大小.Text = join("原图 ", round(图片处理1.FileSize(图像选择器1.Selection) / 1024), " KB → 压缩后 ", round(图片处理1.FileSize(小图) / 1024), " KB")...
Vagrant stuck connection timeout retrying
... the GUI of Virtual box to see that it was waiting for input on startup to select whether I wanted to boot directly to ubuntu or safemode etc.
To turn on the GUI you have to put this in your vagrant config Vagrantfile:
config.vm.provider :virtualbox do |vb|
vb.gui = true
end
...
Search and replace in Vim across all the project files
I'm looking for the best way to do search-and-replace (with confirmation) across all project files in Vim. By "project files" I mean files in the current directory, some of which do not have to be open.
...
How to enable C++11/C++0x support in Eclipse CDT?
...> Dialect
Put -std=c++11 into text box entitled other dialect flags or select ISO C++11 from the Language standard drop down.
For CMake project
Generate eclipse project files (inside your project)
mkdir build
cd build
cmake -G"Eclipse CDT4 - Unix Makefiles" -D CMAKE_BUILD_TYPE=Debug ..
Then...
Get query from java.sql.PreparedStatement [duplicate]
...ut from above code.
Before : com.mysql.jdbc.JDBC4PreparedStatement@fa9cf: SELECT * FROM test WHERE blah1=** NOT SPECIFIED ** and blah2=** NOT SPECIFIED **
After : com.mysql.jdbc.JDBC4PreparedStatement@fa9cf: SELECT * FROM test WHERE blah1='Hello' and blah2='World'
...
Comparison of full text search engine - Lucene, Sphinx, Postgresql, MySQL?
... up the firstname field as shown.
http://localhost:8983/solr/collection1/select?q=firstname:john^2&lastname:john
As you can see, firstname field is boosted up with a score of 2.
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searching and indexing speed
The speed is unbelievably fast and no compromise o...
How to create an array of 20 random bytes?
How can I create an array of 20 random bytes in Java?
6 Answers
6
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Has anyone actually implemented a Fibonacci-Heap efficiently?
...g/fibonacci_heap.hpp. This file has apparently been in pending/ for years and by my projections will never be accepted. Also, there have been bugs in that implementation, which were fixed by my acquaintance and all-around cool guy Aaron Windsor. Unfortunately, most of the versions of that file th...