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How do I get a substring of a string in Python?
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>>> x = "Hello World!"
>>> x[2:]
'llo World!'
>>> x[:2]
'He'
>>> x[:-2]
'Hello Worl'
>>> x[-2:]
'd!'
>>> x[2:-2]
'llo Worl'
Python calls this concept "slicing" and it works on more t...
How to get values from IGrouping
...gt;();
IEnumerable<IGrouping<int, smth>> groups = list.GroupBy(x => x.id);
IEnumerable<smth> smths = groups.SelectMany(group => group);
List<smth> newList = smths.ToList();
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Do on-demand Mac OS X cloud services exist, comparable to Amazon's EC2 on-demand instances? [closed]
Amazon's EC2 service offers a variety of Linux and Windows OS choices, but I haven't found a service offering a similar "rent by the hour" service for a remote Mac OS X virtual machine. Does such a service exist? (iCloud looks to be just a data storage service, rather than a service allowing remot...
How to remove local (untracked) files from the current Git working tree
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Random Gaussian Variables
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Jarrett's suggestion of using a Box-Muller transform is good for a quick-and-dirty solution. A simple implementation:
Random rand = new Random(); //reuse this if you are generating many
double u1 = 1.0-rand.NextDouble(); //uniform(0,1] random doubles
double...
Why use a prime number in hashCode?
...ndering why is that primes are used in a class's hashCode() method? For example, when using Eclipse to generate my hashCode() method there is always the prime number 31 used:
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Is inline assembly language slower than native C++ code?
...fluence performance (as you saw in this case).
You can always produce an example where handmade assembly code is better than compiled code but usually it's a fictional example or a single routine not a true program of 500.000+ lines of C++ code). I think compilers will produce better assembly code ...
Difference between `mod` and `rem` in Haskell
What exactly is the difference between mod and rem in Haskell?
4 Answers
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What is a sealed trait?
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A sealed trait can be extended only in the same file as its declaration.
They are often used to provide an alternative to enums. Since they can be only extended in a single file, the compiler knows every possible subtypes and can reason about it.
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JavaScript by reference vs. by value [duplicate]
...le does change the underlying object.
So, to work through some of your examples:
function f(a,b,c) {
// Argument a is re-assigned to a new value.
// The object or primitive referenced by the original a is unchanged.
a = 3;
// Calling b.push changes its properties - it adds
//...