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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: '...
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...
Python - abs vs fabs
...(-2))
Out[7]: int
In [8]: type(abs(-2.0))
Out[8]: float
In [9]: type(abs(3+4j))
Out[9]: float
In [10]: type(math.fabs(-2))
Out[10]: float
In [11]: type(math.fabs(-2.0))
Out[11]: float
In [12]: type(math.fabs(3+4j))
---------------------------------------------------------------------------
Type...
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...
Swapping column values in MySQL
...t. This method doesn't swap the values if one of them is NULL. Use method #3 that doesn't have this limitation.
UPDATE swap_test SET x=y, y=@temp WHERE (@temp:=x) IS NOT NULL;
This method was offered by Dipin in, yet again, the comments of http://beerpla.net/2009/02/17/swapping-column-values-in-mys...
How do I compare two hashes?
...
163
You can compare hashes directly for equality:
hash1 = {'a' => 1, 'b' => 2}
hash2 = {'a' =...
What is the difference between Ruby 1.8 and Ruby 1.9
...
Array.to_s Now Contains Punctuation
Ruby 1.9
irb(main):001:0> [1,2,3].to_s
=> "[1, 2, 3]"
Ruby 1.8.6
irb(main):001:0> [1,2,3].to_s
=> "123"
Action: Use .join instead
Colon No Longer Valid In When Statements
Ruby 1.9
irb(main):001:0> case 'a'; when /\w/: puts 'word'; end...
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...
Uninitialized constant ActiveSupport::Dependencies::Mutex (NameError)
...
137
This is an incompatibility between Rails 2.3.8 and recent versions of RubyGems. Upgrade to the ...
Reverse Range in Swift
...
Update For latest Swift 3 (still works in Swift 4)
You can use the reversed() method on a range
for i in (1...5).reversed() { print(i) } // 5 4 3 2 1
Or stride(from:through:by:) method
for i in stride(from:5,through:1,by:-1) { print(i) } // 5 4...