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Group by multiple columns in dplyr, using string vector input
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Since this question was posted, dplyr added scoped versions of group_by (documentation here). This lets you use the same functions you would use with select, like so:
data = data.frame(
asihckhdoydkhxiydfgfTgdsx = sample(LETTERS[1:3], 100, replace=TRUE),
a30mvxigxkghc5cdsvxvyv0ja = s...
Guaranteed lifetime of temporary in C++?
... a "full-expression" in this case: printf("%s", strdup(std::string("$$$").c_str()) ); ?I mean if strdup(std::string("$$$").c_str()) is taken as the full expression, then the pointer that strdup sees is valid. If std::string("$$$").c_str() is a full expression, then the pointer that strdup sees is in...
Nested or Inner Class in PHP
...* simulating protected InnerClasses
*/
protected function __construct() {}
/* This magic method is called everytime an inaccessible method is called
* (either by visibility contrains or it doesn't exist)
* Here we are simulating shared protected methods a...
How to add spacing between UITableViewCell
...l the border will be smaller. How can I fix it?
– Bad_Developer
Mar 24 '17 at 11:09
1
Hey, Husam....
Email validation using jQuery
...javascript for that:
function isEmail(email) {
var regex = /^([a-zA-Z0-9_.+-])+\@(([a-zA-Z0-9-])+\.)+([a-zA-Z0-9]{2,4})+$/;
return regex.test(email);
}
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Why is SQL Server 2008 Management Studio Intellisense not working?
... without server, decided to install sp1 sms.
– Johnny_D
Mar 29 '12 at 12:08
1
I tried King's repa...
NUnit Test Run Order
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You mean you called your tests, for example, 001_first_test 002_second_test and so on?
– ashes999
Feb 15 '12 at 20:48
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How to tell Eclipse Workspace?
...ages simple list of last time opened workspaces which is stored as a RECENT_WORKSPACES key in org.eclipse.ui.ide.prefs file. The workspace name shown in this dialog is the first one from this list.
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When should you use constexpr capability in C++11?
...lues over and over?
int func (int n) {
static std::map<int, int> _cached;
if (_cached.find (n) == _cached.end ())
_cached[n] = n > 0 ? n + func (n-1) : n;
return _cached[n];
}
The result
By introducing your silly optimization, you just broke every usage of your function th...
Eclipse: Enable autocomplete / content assist
... Change the default in Auto activation triggers for Java to ._abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ stackoverflow.com/questions/1959946/…
– ftvs
Nov 6 '13 at 3:52
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