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How to reorder data.table columns (without copying)
... 2 2
# [3,] 0.3297416 1 3
From ?setcolorder:
In data.table parlance, all set* functions change their input by reference. That is, no copy is made at all, other than temporary working memory, which is as large as one column.
so should be pretty efficient. See ?setcolorder for details.
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Why is __init__() always called after __new__()?
... new instance.
__new__ is the first step of instance creation. It's called first, and is
responsible for returning a new
instance of your class.
In contrast,
__init__ doesn't return anything; it's only responsible for initializing the
instance after it's been created.
In ge...
Reference: Comparing PHP's print and echo
...hat while they appear to users as two distinct constructs, they are both really shades of echo if you get down to basics, i.e. look at the internal source code. That source code involves the parser as well as opcode handlers. Consider a simple action such as displaying the number zero. Whether you ...
Why cast an unused function parameter value to void?
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@Benoit what does casting to void actually do? Is its only function to show the compiler that you're intentionally ignoring something or does (void) actually do something and when the compiler sees it, it'll just count it as having done something with the variabl...
Build .so file from .c file using gcc command line
...lo.c
to do it in one step. – Jonathan Leffler
I also suggest to add -Wall to get all warnings, and -g to get debugging information, to your gcc commands. – Basile Starynkevitch
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How to refresh / invalidate $resource cache in AngularJS
..., thank you! Exactly what I was looking for. For those wondering, you can call $cacheFactory.get('$http').remove(key), with key being the relative URL of your resource (ex: /api/user/current/51a9020d91799f1e9b8db12f).
– Alexandre Bulté
Jun 12 '13 at 12:25
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Return from lambda forEach() in java
...ching player from the (ordered) stream but simply any matching item. This allows for better efficiency when there's parallelism involved.
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How exactly do Django content types work?
I'm really having a difficult time grasping the concept of Django's content types. It feels very hackish and, ultimately, against how Python tends to do things. That being said, if I'm going to use Django then I have to work within the confines of the framework.
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What are the risks of running 'sudo pip'?
Occasionally I run into comments or responses that state emphatically that running pip under sudo is "wrong" or "bad", but there are cases (including the way I have a bunch of tools set up) where it is either much simpler, or even necessary to run it that way.
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Is there any way to put malicious code into a regular expression?
...o solve. These may only show up on particular input data, but one can generally create one wherein this doesn’t matter.
Which ones these are will depend somewhat on how smart the regex compiler you’re using happens to be, because some of these can be detected during compilation time. Regex com...