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How to convert a boolean array to an int array
...d to int in many cases, so you can add it to int arrays without having to explicitly convert it:
>>> x
array([ True, False, True], dtype=bool)
>>> x + [1, 2, 3]
array([2, 2, 4])
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why is plotting with Matplotlib so slow?
...matplotlib and I'm quite disappointed with the performance. The following example is modified from SciPy examples and gives me only ~ 8 frames per second!
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Mod of negative number is melting my brain
...
I always use my own mod function, defined as
int mod(int x, int m) {
return (x%m + m)%m;
}
Of course, if you're bothered about having two calls to the modulus operation, you could write it as
int mod(int x, int m) {
int r = x%m;
return r<0 ? r+m : r;
}
or varian...
How to make a great R reproducible example
...or guidance on mailing lists and here on Stack Overflow, a reproducible example is often asked and always helpful.
23 An...
What is the most pythonic way to check if an object is a number?
...from fractions import Fraction
... for n in [2, 2.0, Decimal('2.0'), complex(2, 0), Fraction(2, 1), '2']:
... print(f'{n!r:>14} {isinstance(n, Number)}')
2 True
2.0 True
Decimal('2.0') True
(2+0j) True
Fraction(2, 1) True
'2' False
This is, o...
Check that an email address is valid on iOS [duplicate]
... @"^[A-Z0-9a-z\\._%+-]+@([A-Za-z0-9-]+\\.)+[A-Za-z]{2,4}$";
NSString *laxString = @"^.+@([A-Za-z0-9-]+\\.)+[A-Za-z]{2}[A-Za-z]*$";
NSString *emailRegex = stricterFilter ? stricterFilterString : laxString;
NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailReg...
Counting the number of True Booleans in a Python List
...True)
2
This is actually more efficient than sum, as well as being more explicit about the intent, so there's no reason to use sum:
In [1]: import random
In [2]: x = [random.choice([True, False]) for i in range(100)]
In [3]: %timeit x.count(True)
970 ns ± 41.1 ns per loop (mean ± std. dev. of...
Convert tuple to list and back
...nswered May 6 '14 at 14:27
KhonixKhonix
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...
What are the differences between concepts and template constraints?
...oustrup consider the following relationship:
Concepts = Constraints + Axioms
To quickly summarise their meanings:
Constraint - A predicate over statically evaluable properties of a type. Purely syntactic requirements. Not a domain abstraction.
Axioms - Semantic requirements of types that are...
What's the difference between a proc and a lambda in Ruby?
...rguments passed to it. From ri Kernel#lambda:
Equivalent to Proc.new, except the resulting Proc objects check the number of parameters passed when called.
An example:
p = Proc.new {|a, b| puts a**2+b**2 } # => #<Proc:0x3c7d28@(irb):1>
p.call 1, 2 # => 5
p.call 1 # => NoMethodEr...