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Most efficient way to prepend a value to an array
... Only one issue with this solution. Doesn't unshift() return its length, and not the array as in this answer? w3schools.com/jsref/jsref_unshift.asp
– iDVB
Mar 8 '15 at 5:36
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How do I write a correct micro-benchmark in Java?
How do you write (and run) a correct micro-benchmark in Java?
11 Answers
11
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Find which version of package is installed with pip
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As of pip 1.3, there is a pip show command.
$ pip show Jinja2
---
Name: Jinja2
Version: 2.7.3
Location: /path/to/virtualenv/lib/python2.7/site-packages
Requires: markupsafe
In older versions, pip freeze and grep should do the job nicely.
$ pip freeze | grep Ji...
Windows batch files: .bat vs .cmd?
As I understand it, .bat is the old 16-bit naming convention, and .cmd is for 32-bit Windows, i.e., starting with NT. But I continue to see .bat files everywhere, and they seem to work exactly the same using either suffix. Assuming that my code will never need to run on anything older than NT, d...
C++ unordered_map using a custom class type as the key
... things:
A hash function; this must be a class that overrides operator() and calculates the hash value given an object of the key-type. One particularly straight-forward way of doing this is to specialize the std::hash template for your key-type.
A comparison function for equality; this is require...
Generate random numbers with a given (numerical) distribution
... You can then use the rvs() method of the distribution object to generate random numbers.
As pointed out by Eugene Pakhomov in the comments, you can also pass a p keyword parameter to numpy.random.choice(), e.g.
numpy.random.choice(numpy.arange(1, 7), p=[0.1, 0.05, 0.05, 0.2, 0.4, 0.2])
If you a...
How efficient is locking an unlocked mutex? What is the cost of a mutex?
...bunch of mutexes or a single one for an object.
If you have many threads and the access to the object happens often, then multiple locks would increase parallelism. At the cost of maintainability, since more locking means more debugging of the locking.
How efficient is it to lock a mutex? I.e....
Using Java with Nvidia GPUs (CUDA)
I'm working on a business project that is done in Java, and it needs huge computation power to compute business markets. Simple math, but with huge amount of data.
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How do you pass multiple enum values in C#?
...ine the enum, just attribute it with [Flags], set values to powers of two, and it will work this way.
Nothing else changes, other than passing multiple values into a function.
For example:
[Flags]
enum DaysOfWeek
{
Sunday = 1,
Monday = 2,
Tuesday = 4,
Wednesday = 8,
Thursday = 16,
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Most efficient way to store thousand telephone numbers
...digits left. We view these remaining five digits as 17-bit binary integers and store k of those bits using one method and 17 - k = m with a different method, determining k at the end to minimize the required space.
We first sort the phone numbers (all reduced to 5 decimal digits). Then we count how...