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What's the difference between lists enclosed by square brackets and parentheses in Python?
...you can change its contents:
>>> x = [1,2]
>>> x.append(3)
>>> x
[1, 2, 3]
while tuples are not:
>>> x = (1,2)
>>> x
(1, 2)
>>> x.append(3)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: '...
Algorithm for Determining Tic Tac Toe Game Over
...
133
You know a winning move can only happen after X or O has made their most recent move, so you ca...
Does Python have an ordered set?
...ferred to from the Python 2 Documentation. This runs on Py2.6 or later and 3.0 or later without any modifications. The interface is almost exactly the same as a normal set, except that initialisation should be done with a list.
OrderedSet([1, 2, 3])
This is a MutableSet, so the signature for .uni...
Uninitialized constant ActiveSupport::Dependencies::Mutex (NameError)
...
137
This is an incompatibility between Rails 2.3.8 and recent versions of RubyGems. Upgrade to the ...
What is the bower (and npm) version syntax?
...
342
In a nutshell, the syntax for Bower version numbers (and NPM's) is called SemVer, which is sho...
How to get row from R data.frame
...
130
x[r,]
where r is the row you're interested in. Try this, for example:
#Add your data
x <...
How do I compare two hashes?
...
163
You can compare hashes directly for equality:
hash1 = {'a' => 1, 'b' => 2}
hash2 = {'a' =...
How do you get the magnitude of a vector in Numpy?
...ray -- say x.norm() -- but oh well).
import numpy as np
x = np.array([1,2,3,4,5])
np.linalg.norm(x)
You can also feed in an optional ord for the nth order norm you want. Say you wanted the 1-norm:
np.linalg.norm(x,ord=1)
And so on.
...
Numpy: Get random set of rows from 2D array
...
>>> A = np.random.randint(5, size=(10,3))
>>> A
array([[1, 3, 0],
[3, 2, 0],
[0, 2, 1],
[1, 1, 4],
[3, 2, 2],
[0, 1, 0],
[1, 3, 1],
[0, 4, 1],
[2, 4, 2],
[3, 3, 1]])
>>> idx = np.ran...
pandas GroupBy columns with NaN (missing) values
...
138
This is mentioned in the Missing Data section of the docs:
NA groups in GroupBy are automatica...