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Sort rows in data.table in decreasing order on string key `order(-x,v)` gives error on data.table 1.
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Update
data.table v1.9.6+ now supports OP's original attempt and the following answer is no longer necessary.
You can use DT[order(-rank(x), y)].
x y v
1: c 1 7
2: c 3 8
3: c 6 9
4: b 1 1
5: b 3 2
6: b 6 3
7: a 1 4
8: a 3 5
9: a 6 6
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how to provide a swap function for my class?
...dummy
void swap(Bar& lhs, Bar& rhs) {
// ...
}
}
If swap is now used as shown in 1), your function will be found. Also, you may make that function a friend if you absolutely need to, or provide a member swap that is called by the free function:
// version 1
class Bar{
public:
frie...
What's the difference between HEAD, working tree and index, in Git?
... 1 -> 2 -> 3 -> 4 where 1 is the first commit and 4 is the last)
Now we know what is happening in the project.
But to know what is happening right here, right now there is a special reference called HEAD. It serves two major purposes:
it tells Git which commit to take files from when yo...
AI2 Keep Awake
... Version 1.1 (2024-11-03) Internal adjustments Notice: The lifespan of the device battery will be significantly reduced by using this extension. Do not set WakeLocks if you do not really need them, use them as rarely as possible and release them as soon as possible. If actions ar...
Unignore subdirectories of ignored directories in Git
...fic example refers to a global gitignore which I should have mentioned. I know I can force add items, but I'll have to do that if any new items are added, as well as initially for each new repository. Does the .keep ensure the contents are not ignored?
– Wil
Ma...
Bootstrap dropdown sub menu missing
...Mark Otto..
"Submenus just don't have much of a place on the web right now, especially the mobile web. They will be removed with 3.0" - https://github.com/twbs/bootstrap/pull/6342
But, with a little extra CSS you can get the same functionality.
Bootstrap 4 (navbar submenu on hover)
.navbar-n...
How can I make git accept a self signed certificate?
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@Flow -- I completely concur. I've edited this (now quite old) answer to be more polemical about disabling TLS/SSL cert verification.
– Christopher
Aug 17 '15 at 19:01
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In what cases do I use malloc and/or new?
... or throw ...
}
return new (mem)T(std::forward(args)...);
}
};
Now though in fixing all the issues we identified so far we've practically reinvented the default new operator. If you're going to use malloc and placement new then you might as well just use new to begin with!
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Catch multiple exceptions at once?
It is discouraged to simply catch System.Exception . Instead, only the "known" exceptions should be caught.
27 Answers
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Why maven? What are the benefits? [closed]
...for it in your
dependency management... there is no
'I'll just do this now and fix it
later' implementations.
Dependency Management is clearly declared. with the dependency
management mechanism you have to try
to screw up your jar
versioning...there is none of the
classic problem of ...