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Unique combination of all elements from two (or more) vectors
...sing, which works better than the classic expand.grid function because (1) strings are not converted into factors and (2) the sorting is more intuitive:
library(tidyr)
a <- c("ABC", "DEF", "GHI")
b <- c("2012-05-01", "2012-05-02", "2012-05-03", "2012-05-04", "2012-05-05")
crossing(a, b)
# ...
Set time part of DateTime in ruby
...
Also to note that the last argument needs to be a string of the timezone e.g.("-0700") for MST, not an integer
– Donavan White
Nov 24 '15 at 17:20
2
...
How do you use the Immediate Window in Visual Studio?
...s say this is what your class looks like:
private class Foo
{
public string GetMessage()
{
return "hello";
}
}
If the object already exists in memory and it’s in scope, then you can call it in the Immediate Window as long as it has been instantiated before your current brea...
Multiple commands in gdb separated by some sort of delimiter ';'?
...active if the command
# that invoked them is interactive.
# to_string is false. We just want to write the output of the commands, not capture it.
gdb.execute(fragment, from_tty=from_tty, to_string=False)
print()
Cmds()
end
example invocation:
$ gdb
(gdb) cmds echo hi ; e...
Swift Programming: getter/setter in stored property
...ape {
var sideLength: Double = 0.0
init(sideLength: Double, name: String) {
self.sideLength = sideLength
super.init(name: name)
numberOfSides = 3
}
var perimeter: Double {
get {
return 3.0 * sideLength
}
set {
sideLength = newValu...
Why can't I access DateTime->date in PHP's DateTime class?
...
This is slight faster than using format() because format() formats a timestring that has already been formatted. Especially if you do it many times in a loop.
However this is not a regular behaviour of PHP. A bugreport has already been filed as @Nile mentioned in the comments above.
...
Is null reference possible?
...red_ptr<Error>> _instances;
static Error& NewInstance(const string& name, bool isNull = false);
private:
bool _isNull;
Error(const string& name, bool isNull = false) : _name(name), _isNull(isNull) {};
Error() {};
Error(const Error& src) {};
Error& operator=(...
How does PHP 'foreach' actually work?
...hat, in all cases but 3, the array is modified during the loop, while this extra reference is alive. This triggers a clone, and that explains what's going on here!
Here is an excellent article for another side effect of this copy-on-write behaviour: The PHP Ternary Operator: Fast or not?
...
What are all the possible values for HTTP “Content-Type” header?
...attribute "=" value
attribute := token
value := token / quoted-string
token := 1*
tspecials := "(" / ")" / "<" / ">" / "@" ; Must be in
/ "," / ";" / ":" / "\" / <"> ; quoted-string,
/ "/" / "[" / "]" / "?" / "." ; to use within
...
XML attribute vs XML element
...butes vs. elements:
Use elements for long running text (usually those of string or
normalizedString types)
Do not use an attribute if there is grouping of two values (e.g.
eventStartDate and eventEndDate) for an element. In the previous example,
there should be a new element for "event" which ma...