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Difference between reduce and foldLeft/fold in functional programming (particularly Scala and Scala
...ase of foldLeft
scala> val intParList: ParSeq[Int] = (1 to 100000).map(_ => scala.util.Random.nextInt()).par
scala> timeMany(1000, intParList.reduce(_ + _))
Took 462.395867 milli seconds
scala> timeMany(1000, intParList.foldLeft(0)(_ + _))
Took 2589.363031 milli seconds
reduce vs fo...
Find the nth occurrence of substring in a string
... more Pythonic version of the straightforward iterative solution:
def find_nth(haystack, needle, n):
start = haystack.find(needle)
while start >= 0 and n > 1:
start = haystack.find(needle, start+len(needle))
n -= 1
return start
Example:
>>> find_nth("fo...
Printf width specifier to maintain precision of floating-point value
...be to print one seventh as in:
#include <float.h>
int Digs = DECIMAL_DIG;
double OneSeventh = 1.0/7.0;
printf("%.*e\n", Digs, OneSeventh);
// 1.428571428571428492127e-01
But let's dig deeper ...
Mathematically, the answer is "0.142857 142857 142857 ...", but we are using finite precision...
Fastest way to get the first object from a queryset in django?
...ust do the above and it will only pull the first. You could even use .order_by() to ensure you get the first you want.
Be sure to add the .get() or else you will get a QuerySet back and not an object.
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Finding the index of an item in a list
...atch, you can give index a hint. For instance, in this snippet, l.index(999_999, 999_990, 1_000_000) is roughly five orders of magnitude faster than straight l.index(999_999), because the former only has to search 10 entries, while the latter searches a million:
>>> import timeit
>>&g...
Convert a Scala list to a tuple?
... I know of, but it's easy enough to make your own, e.g. case class Vec3[A](_1: A, _2: A, _3: A)
– Tom Crockett
Sep 16 '14 at 6:43
...
Is cout synchronized/thread-safe?
... @ildjarn - No, @edA-qa mort-ora-y is correct. As long as cout.sync_with_stdio() is true, using cout to output characters from multiple threads without additional synchronization is well-defined, but only on the level of individual bytes. Thus, cout << "ab"; and cout << "cd" exec...
Find out how much memory is being used by an object in Python [duplicate]
...
Try this:
sys.getsizeof(object)
getsizeof() calls the object’s __sizeof__ method and adds an additional garbage collector overhead if the object is managed by the garbage collector.
A recursive recipe
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How disable Copy, Cut, Select, Select All in UITextView
... your /, file where you need this behaviour.
– markus_p
Apr 3 '12 at 10:07
4
This only works as a...
How to access app.config in a blueprint?
...horisation.py which in a package api. I am initializing the blueprint in __init__.py which is used in authorisation.py .
...