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Assign multiple columns using := in data.table, by group
What is the best way to assign to multiple columns using data.table ? For example:
2 Answers
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Create Directory if it doesn't exist with Ruby
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You are probably trying to create nested directories. Assuming foo does not exist, you will receive no such file or directory error for:
Dir.mkdir 'foo/bar'
# => Errno::ENOENT: No such file or directory - 'foo/bar'
To cre...
What is “point free” style (in Functional Programming)?
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Just look at the Wikipedia article to get your definition:
Tacit programming (point-free programming) is a programming paradigm in which a function definition does not include information regarding its arguments, using com...
Does .NET have a way to check if List a contains all items in List b?
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If you're using .NET 3.5, it's easy:
public class ListHelper<T>
{
public static bool ContainsAllItems(List<T> a, List<T> b)
{
return !b.Except(a).Any();
}
}
This checks whether there are an...
“icon-bar” in twitter bootstrap navigation bar
I cannot understand what the following code means in terms of icon-bar :
3 Answers
3
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Assign one struct to another in C
Can you assign one instance of a struct to another, like so:
5 Answers
5
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Literal suffix for byte in .NET?
...here is any way to declare a byte variable in a short way like floats or doubles? I mean like 5f and 5d . Sure I could write byte x = 5 , but that's a bit inconsequential if you use var for local variables.
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What is the difference between object keys with quotes and without quotes?
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No, the quotes do not make a difference (unless, as you noted, you want to use a key that’s not a valid JavaScript identifier).
As a side note, the JSON data exchange format does require double quotes around identifiers (and does n...
getSupportActionBar from inside of Fragment ActionBarCompat
I'm starting a new project that uses the AppCompat/ActionBarCompat in v7 support library. I'm trying to figure out how to use the getSupportActionBar from within a fragment. My activity that hosts the fragment extends ActionBarActivity , but I don't see a similar support class for Fragments.
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Mockito: Inject real objects into private @Autowired fields
I'm using Mockito's @Mock and @InjectMocks annotations to inject dependencies into private fields which are annotated with Spring's @Autowired :
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