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What is more efficient? Using pow to square or just multiply it with itself?
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I tested the performance difference between x*x*... vs pow(x,i) for small i using this code:
#include <cstdlib>
#include <cmath>
#include <boost/date_time/posix_time/posix_time.hpp>
inline boost::posix_time::ptime now()
{
return boost::posix_tim...
Is it possible to have multiple statements in a python lambda expression?
... the second lowest item from a lambda by sorting the list?
A. Yes. As alex's answer points out, sorted() is a version of sort that creates a new list, rather than sorting in-place, and can be chained. Note that this is probably what you should be using - it's bad practice for your map to have sid...
Python: print a generator expression?
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Quick answer:
Doing list() around a generator expression is (almost) exactly equivalent to having [] brackets around it. So yeah, you can do
>>> list((x for x in string.letters if x in (y for y in "BigMan on campus")))
But you can just as well do
>>>...
What is the good python3 equivalent for auto tuple unpacking in lambda?
...rder to read than your two suggestions:
min(points, key=lambda p: (lambda x,y: (x*x + y*y))(*p))
update Python 3.8
As of now, Python 3.8 alpha1 is available, and PEP 572- assignment expressions are implemented.
So, if one uses a trick to execute multiple expressions inside a lambda - I usually ...
Is there shorthand for returning a default value if None in Python? [duplicate]
In C#, I can say x ?? "" , which will give me x if x is not null, and the empty string if x is null. I've found it useful for working with databases.
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Split a vector into chunks in R
...[53] 4 5 4 5 5 8 7 7 7 6 2 4 3 3 8 11 6 6 1 8 4
> max <- 20
> x <- seq_along(d)
> d1 <- split(d, ceiling(x/max))
> d1
$`1`
[1] 3 1 11 4 1 2 3 2 4 10 10 2 7 4 6 6 2 1 1 2
$`2`
[1] 3 8 3 10 7 4 3 4 4 1 1 7 2 4 6 0 5 7 4 6
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Sorting list based on values from another list?
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Shortest Code
[x for _,x in sorted(zip(Y,X))]
Example:
X = ["a", "b", "c", "d", "e", "f", "g", "h", "i"]
Y = [ 0, 1, 1, 0, 1, 2, 2, 0, 1]
Z = [x for _,x in sorted(zip(Y,X))]
print(Z) # ["a", "d", "h", "b", "c", "e", "i...
What does (x ^ 0x1) != 0 mean?
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The XOR operation (x ^ 0x1) inverts bit 0. So the expression effectively means: if bit 0 of x is 0, or any other bit of x is 1, then the expression is true.
Conversely the expression is false if x == 1.
So the test is the same ...
How do I compute derivative using Numpy?
How do I calculate the derivative of a function, for example
8 Answers
8
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How to convert a std::string to const char* or char*?
...finished using it
delete[] writable;
Edit: Notice that the above is not exception safe. If anything between the new call and the delete call throws, you will leak memory, as nothing will call delete for you automatically. There are two immediate ways to solve this.
boost::scoped_array
boost::sco...