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Speed up the loop operation in R
I have a big performance problem in R. I wrote a function that iterates over a data.frame object. It simply adds a new column to a data.frame and accumulates something. (simple operation). The data.frame has roughly 850K rows. My PC is still working (about 10h now) and I have no idea about the...
Handling a colon in an element ID in a CSS selector [duplicate]
JSF is setting the ID of an input field to search_form:expression . I need to specify some styling on that element, but that colon looks like the beginning of a pseudo-element to the browser so it gets marked invalid and ignored. Is there anyway to escape the colon or something?
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Division of integers in Java [duplicate]
...double, the other will be implicitly converted. But I prefer to do both, for symmetry.
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Bower and devDependencies vs dependencies
... that it installs 1.0.8, I uninstalled the angular components, however the original bower.json file had angular-mocks and angular-scenario under 'devDependencies' when I re-add all the 1.2.0-rc.2 components angular-mocks and angular-scenario under dependencies instead of devDependencies.
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How come a non-const reference cannot bind to a temporary object?
Why is it not allowed to get non-const reference to a temporary object,
which function getx() returns? Clearly, this is prohibited by C++ Standard
but I am interested in the purpose of such restriction, not a reference to the standard.
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Command substitution: backticks or dollar sign / paren enclosed? [duplicate]
...ed, and followed by my response.
What's the preferred syntax, and why? Or are they pretty much interchangeable?
I would say that the $(some_command) form is preferred over the `some_command` form. The second form, using a pair of backquotes (the "`" character, also called a backtick and a grav...
Using sed to mass rename files
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First, I should say that the easiest way to do this is to use the
prename or rename commands.
On Ubuntu, OSX (Homebrew package rename, MacPorts package p5-file-rename), or other systems with perl rename (prename):
rename s/0000/000/ F0000*
or on systems with rename from util-linux-ng, such as R...
Utilizing multi core for tar+gzip/bzip compression/decompression
I normally compress using tar zcvf and decompress using tar zxvf (using gzip due to habit).
6 Answers
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Rails update_attributes without save?
Is there an alternative to update_attributes that does not save the record?
4 Answers
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Flatten an Array of Arrays in Swift
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Just to state this more generally, flatMap is available as of Swift 1.2.
– Mick MacCallum
Apr 24 '15 at 4:56
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