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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...
python numpy ValueError: operands could not be broadcast together with shapes
In numpy, I have two "arrays", X is (m,n) and y is a vector (n,1)
6 Answers
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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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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...
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...
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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What is the difference between range and xrange functions in Python 2.X?
Apparently xrange is faster but I have no idea why it's faster (and no proof besides the anecdotal so far that it is faster) or what besides that is different about
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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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