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Sort rows in data.table in decreasing order on string key `order(-x,v)` gives error on data.table 1.
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Update
data.table v1.9.6+ now supports OP's original attempt and the following answer is no longer necessary.
You can use DT[order(-rank(x), y)].
x y v
1: c 1 7
2: c 3 8
3: c 6 9
4: b 1 1
5: b 3 2
6: b 6 3
7: a 1 4
8: a 3 5
9: a 6 6
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Android Studio says “cannot resolve symbol” but project compiles
I'm importing twitter4j in AndroidStudio, using the following in my build.gradle:
27 Answers
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Real mouse position in canvas [duplicate]
....clientY - rect.top
};
}
Just call it from your event with the event and canvas as arguments. It returns an object with x and y for the mouse positions.
As the mouse position you are getting is relative to the client window you'll have to subtract the position of the canvas element to convert...
Automatic creation date for Django model form objects?
What's the best way to set a creation date for an object automatically, and also a field that will record when the object was last updated?
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How to loop through file names returned by find?
...st). If you have time, read through the rest to see several different ways and the problems with most of them.
The full answer:
The best way depends on what you want to do, but here are a few options. As long as no file or folder in the subtree has whitespace in its name, you can just loop over ...
'is' versus try cast with null check
...// only one cast
if (myObjRef != null)
{
// myObjRef is already MyType and doesn't need to be cast again
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}
C# 7.0 supports a more compact syntax using pattern matching:
if (myObj.myProp is MyType myObjRef)
{
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}
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Remove last character from C++ string
...is to use the function that is intended for this task, it's called erase() and the code is: st.erase(st.size()-1). This would be called a "mutating version".
– Czarek Tomczak
Jan 19 '13 at 14:46
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How to display the function, procedure, triggers source code in postgresql?
How to print functions and triggers sourcecode in postgresql? please let me know if any one know the query to display the function, triggers source code.
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How can I make a time delay in Python? [duplicate]
...l... it'll print less frequently than that, because it takes time to print and handle all the buffers that entails (possibly doing a kernel context switch), and to register the alarm signal, but... yeah. A little under once per minute.
– Parthian Shot
Jun 17 '1...
Why does Oracle 9i treat an empty string as NULL?
..., but that doesn't do much to tell me why this is the case. As I understand the SQL specifications, ' ' is not the same as NULL -- one is a valid datum, and the other is indicating the absence of that same information.
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