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data.table vs dplyr: can one do something well the other can't or does poorly?
...j and by together is by design. By keeping related operations together, it allows to easily optimise operations for speed and more importantly memory usage, and also provide some powerful features, all while maintaining the consistency in syntax.
1. Speed
Quite a few benchmarks (though mostly on g...
rmagick gem install “Can't find Magick-config”
I get the error shown below when attempting to install the rmagick gem. I am on Snowleopard 10.6 using RVM, Ruby 1.9.2-head and Rails 3.05. Responses to similar questions recommended installing ImageMagick, which I successfully did. Other suggested installing the "libmagick9-dev library", however, I...
Line continuation for list comprehensions or generator expressions in python
...so you can pretty much do as you please. I'd personally prefer
[something_that_is_pretty_long
for something_that_is_pretty_long
in somethings_that_are_pretty_long]
The reason why \ isn't appreciated very much is that it appears at the end of a line, where it either doesn't stand out or needs...
How to version control a record in a database
...O table. Happy days.
Then, I would create a FOO_HISTORY table. This has all the columns of the FOO table. The primary key is the same as FOO plus a RevisionNumber column. There is a foreign key from FOO_HISTORY to FOO. You might also add columns related to the revision such as the UserId and R...
Developing C# on Linux
... is runnable on top of .Net framework. So as long as it is possible to install .Net framework in OS it can run the application. You got to aware of the version though ;)
– Shiham
Jun 26 '12 at 8:32
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Rails detect if request was AJAX
... you're using :remote => true in your links or forms, you'd do:
respond_to do |format|
format.js { #Do some stuff }
You can also check before the respond_to block by calling request.xhr?.
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Most lightweight way to create a random string and a random hexadecimal number
...165037870407104
9.0292739868164062
5.2836320400238037
t3 only makes one call to the random module, doesn't have to build or read a list, and then does the rest with string formatting.
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impr...
Should I use char** argv or char* argv[]?
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As you are just learning C, I recommend you to really try to understand the differences between arrays and pointers first instead of the common things.
In the area of parameters and arrays, there are a few confusing rules that should be clear before going on. First, what ...
How can I list ALL DNS records?
Is there any way I can list ALL DNS records for a domain?
8 Answers
8
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How to get the current date/time in Java [duplicate]
...here's the way to do it:
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(Calendar.getInstance().getTime());
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