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Group by multiple columns in dplyr, using string vector input
I'm trying to transfer my understanding of plyr into dplyr, but I can't figure out how to group by multiple columns.
9 Answ...
What does the constant 0.0039215689 represent?
...was the multiply-by-reciprocal optimization. So I checked in my calculator and sure enough - I guessed right.
– Mysticial
Mar 24 '14 at 22:08
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WPF datagrid empty row at bottom
...e to explicitly add that line of code to hide the additional row (or check and uncheck the check box)
– Tobias Valinski
Nov 28 '13 at 10:39
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What is the purpose of a plus symbol before a variable?
...icating the if on whether or not d is a non-zero number.
Reference here. And, as pointed out in comments, here.
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UICollectionView current visible cell index
...e in my iPad application.
I have set UICollectionView such that its size and cell size is same, means only once cell is displayed at a time.
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How would you compare jQuery objects?
...etty much nothing is required other than ensuring they are the same length and share identical nodes. Here is a small code snippet. You may even want to convert this into a jquery plugin for your own uses.
jQuery(function($) {
// Two separate jQuery references
var divs = $("div");
var divs2...
How to set selected item of Spinner by value, not by position?
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Suppose your Spinner is named mSpinner, and it contains as one of its choices: "some value".
To find and compare the position of "some value" in the Spinner use this:
String compareValue = "some value";
ArrayAdapter<CharSequence> adapter = ArrayAdapter.crea...
Android: how to check if a View inside of ScrollView is visible?
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@Qberticus How to call the methods ? I am using it and it is always returning false. Please let me know
– KK_07k11A0585
Jun 15 '15 at 14:57
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Why there is no ConcurrentHashSet against ConcurrentHashMap
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@Andrew, I think the motivation behind using a "ConcurrentSet" stems from not the API but rather the implementation - thread safety but without a universal lock - multiple concurrent reads for instance.
–...
How do I check if a property exists on a dynamic anonymous type in c#?
... IsPropertyExist(dynamic settings, string name)
{
if (settings is ExpandoObject)
return ((IDictionary<string, object>)settings).ContainsKey(name);
return settings.GetType().GetProperty(name) != null;
}
var settings = new {Filename = @"c:\temp\q.txt"};
Console.WriteLine(...