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Factors in R: more than an annoyance?
One of the basic data types in R is factors. In my experience factors are basically a pain and I never use them. I always convert to characters. I feel oddly like I'm missing something.
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How do I check if there are duplicates in a flat list?
For example, given the list ['one', 'two', 'one'] , the algorithm should return True , whereas given ['one', 'two', 'three'] it should return False .
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What is the difference between a thread and a fiber?
.../etc.). This means that for threads, data integrity is a big issue because one thread may be stopped in the middle of updating a chunk of data, leaving the integrity of the data in a bad or incomplete state. This also means that the operating system can take advantage of multiple CPUs and CPU cores ...
Python memoising/deferred lookup property decorator
Recently I've gone through an existing code base containing many classes where instance attributes reflect values stored in a database. I've refactored a lot of these attributes to have their database lookups be deferred, ie. not be initialised in the constructor but only upon first read. These attr...
What is “assert” in JavaScript?
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There is no assert in JavaScript (yet; there's talk of adding one, but it's at an early stage). Perhaps you're using some library that provides one. The usual meaning is to throw an error if the expression passed into the function is false; this is part of the general concept of asserti...
Scala: Abstract types vs generics
... can abstract over them.
And what we get conceptually is that we can model one in terms of the other. At least in principle, we can express every sort of parameterization as a form of object-oriented abstraction. So in a sense you could say Scala is a more orthogonal and complete language.
Why?
Wh...
How to normalize a NumPy array to within a certain range?
...ized within a range before it can be written back to a file. This can be done like so:
7 Answers
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Quickly find whether a value is present in a C array?
...roll the loop. Here's a way to do it which incorporates the 3 ideas I mentioned in my comment: Loop unrolling, cache prefetch and making use of the multiple load (ldm) instruction. The instruction cycle count comes out to about 3 clocks per array element, but this doesn't take into account memory de...
Changing the background drawable of the searchview widget
...decides to reimplement internals of SearchView and element with above-mentioned id is not present - the code won't work.
In SDK, the background for text field in SearchView is declared through nine-patches, so we'll do it the same way. You can find original png images in drawable-mdpi directory of ...
Using Python's os.path, how do I go up one directory?
I recently upgrade Django from v1.3.1 to v1.4.
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