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detach all packages while working in R
...
invisible(suppressMessages(suppressWarnings(lapply(c("gsl","fBasics","stringr","stringi","Rmpfr"), require, character.only = TRUE))))
invisible(suppressMessages(suppressWarnings(lapply(names(sessionInfo()$loadedOnly), require, character.only = TRUE))))
sessionInfo()
#the above is a...
How to Calculate Execution Time of a Code Snippet in C++
...without Boost (tested on macOS/iOS):
#include <chrono>
#include <string>
#include <iostream>
#include <math.h>
#include <unistd.h>
class NLTimerScoped {
private:
const std::chrono::steady_clock::time_point start;
const std::string name;
public:
NLTimerSco...
Where does Scala look for implicits?
...something that does support m. A simple example would be the method map on String:
"abc".map(_.toInt)
String does not support the method map, but StringOps does, and there's an implicit conversion from String to StringOps available (see implicit def augmentString on Predef).
Implicit Parameters
...
How to set Bullet colors in UL/LI html lists via CSS without using any images or span tags [duplicat
...or Cmd+S in Mac) and use the actual PNG file instead of the Base64 encoded string
– OMA
Mar 13 '15 at 13:30
...
The necessity of hiding the salt for a hash
..." is that it makes cracking more difficult, but it doesn't try to hide the extra data. If you are trying to get more security by making the salt "secret", then you really just want more bits in your encryption keys.
share
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Convert two lists into a dictionary
...
dict([(k, v) for k, v in zip(keys, values)])
In the first two cases, an extra layer of non-operative (thus unnecessary) computation is placed over the zip iterable, and in the case of the list comprehension, an extra list is unnecessarily created. I would expect all of them to be less performant,...
Reduce, fold or scan (Left/Right)?
...the collection (from A to C):
val abc = List("A", "B", "C")
def add(res: String, x: String) = {
println(s"op: $res + $x = ${res + x}")
res + x
}
abc.reduceLeft(add)
// op: A + B = AB
// op: AB + C = ABC // accumulates value AB in *first* operator arg `res`
// res: String = ABC
abc.foldLe...
Executing multi-line statements in the one-line command-line?
...rehension, lambdas, sys.stdout.write, the "map" builtin, and some creative string interpolation, you can do some powerful one-liners.
The question is, how far do you want to go, and at what point is it not better to write a small .py file which your makefile executes instead?
...
Retrieving parameters from a URL
...n you a list object. You need to get the first element of it if you want a string urlparse.parse_qs(parsed.query)['def'][0]
– raffaem
Jul 9 '17 at 10:11
...
Count(*) vs Count(1) - SQL Server
...ution-time work. The Compilation time work is a trivially small amount of extra work in the current implementation. There is an expansion of the * to all columns in some cases followed by a reduction back to 1 column being output due to how some of the internal operations work in binding and optim...