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Rotating a two-dimensional array in Python
...ider the following two-dimensional list:
original = [[1, 2],
[3, 4]]
Lets break it down step by step:
>>> original[::-1] # elements of original are reversed
[[3, 4], [1, 2]]
This list is passed into zip() using argument unpacking, so the zip call ends up being the equiva...
Getting SyntaxError for print with keyword argument end=' '
...
Are you sure you are using Python 3.x? The syntax isn't available in Python 2.x because print is still a statement.
print("foo" % bar, end=" ")
in Python 2.x is identical to
print ("foo" % bar, end=" ")
or
print "foo" % bar, end=" "
i.e. as a call to...
Returning the product of a list
...rt numpy as np
import numexpr as ne
# from functools import reduce # python3 compatibility
a = range(1, 101)
%timeit reduce(lambda x, y: x * y, a) # (1)
%timeit reduce(mul, a) # (2)
%timeit np.prod(a) # (3)
%timeit ne.evaluate("prod(a)") # (4)
In t...
Python assigning multiple variables to same value? list behavior
...es are naming the same object, use the is operator:
>>> a=b=c=[0,3,5]
>>> a is b
True
You then ask:
what is different from this?
d=e=f=3
e=4
print('f:',f)
print('e:',e)
Here, you're rebinding the name e to the value 4. That doesn't affect the names d and f in any way.
...
How to iterate a loop with index and element in Swift
...
Yes. As of Swift 3.0, if you need the index for each element along with its value, you can use the enumerated() method to iterate over the array. It returns a sequence of pairs composed of the index and the value for each item in the array. F...
How to print a dictionary line by line in Python?
...
13 Answers
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How to format a phone number with jQuery
...
Simple: http://jsfiddle.net/Xxk3F/3/
$('.phone').text(function(i, text) {
return text.replace(/(\d{3})(\d{3})(\d{4})/, '$1-$2-$3');
});
Or: http://jsfiddle.net/Xxk3F/1/
$('.phone').text(function(i, text) {
return text.replace(/(\d\d\d)(\d\d\d)(...
Find value in an array
...rray, and if that's the case, you can use Array#include?(value):
a = [1,2,3,4,5]
a.include?(3) # => true
a.include?(9) # => false
If you mean something else, check the Ruby Array API
share
|
...
Flatten an Array of Arrays in Swift
...
Swift >= 3.0
reduce:
let numbers = [[1,2,3],[4],[5,6,7,8,9]]
let reduced = numbers.reduce([], +)
flatMap:
let numbers = [[1,2,3],[4],[5,6,7,8,9]]
let flattened = numbers.flatMap { $0 }
joined:
let numbers = [[1,2,3],[4],[5,6,7...
How can I obtain the element-wise logical NOT of a pandas Series?
... True, False, True])
In [8]: ~s
Out[8]:
0 False
1 False
2 True
3 False
dtype: bool
Using Python2.7, NumPy 1.8.0, Pandas 0.13.1:
In [119]: s = pd.Series([True, True, False, True]*10000)
In [10]: %timeit np.invert(s)
10000 loops, best of 3: 91.8 µs per loop
In [11]: %timeit ~s
10...