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Group by multiple columns in dplyr, using string vector input
...cumentation 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 = sample(LETTERS[1:3], 100, replace=TRUE),
value = rnorm(100)
)
# get the column...
Creating temporary files in bash
...many shell scripts take the name of the program with
the pid as a suffix and use that as a temporary file name. This kind
of naming scheme is predictable and the race condition it creates is
easy for an attacker to win. A safer, though still inferior, approach
is to make a temporary directo...
Why should I avoid std::enable_if in function signatures
...{}
}
Tag dispatching does not manipulate the overload set, but helps you select exactly the function you want by providing the proper arguments through a compile-time expression (e.g. in a type trait). In my experience, this is much easier to debug and get right. If you are an aspiring library wri...
Commit changes to a different branch than the currently checked out branch with subversion
... It must not be the root of the repository, less to duplicate in that way;
Select TortoiseSVN -> "Branch/tag...";
Set To URL: "svn://host/repository/FooBar/branches/FooBarBranchName";
Make sure [*] Working copy is selected. This will ensure the changes are commited;
Log message: "Experimenting wi...
Which MySQL data type to use for storing boolean values
...
When I do a select from the standard mysql command line client bit fields shows up completely blank. Because of this I prefer TINYINT(1).
– User
Nov 2 '12 at 0:53
...
What exactly does git's “rebase --preserve-merges” do (and why?)
...her part. The differences with --preserve-merges concern which commits are selected for replay and how that replaying works for merge commits.
To be more explicit about the main differences between normal and merge-preserving rebase:
Merge-preserving rebase is willing to replay (some) merge commi...
printf() formatting for hex
...
The # part gives you a 0x in the output string. The 0 and the x count against your "8" characters listed in the 08 part. You need to ask for 10 characters if you want it to be the same.
int i = 7;
printf("%#010x\n", i); // gives 0x00000007
printf("0x%08x\n", i); // gives 0x0...
Null coalescing in powershell
...ll values in the same order as the array created in Step 1.
[0] is used to select the first element of the filtered array.
Simplifying that:
Create an array of possible values, in preferred order
Exclude all null values from the array
Take the first item from the resulting array
Caveats
Unlik...
Look up all descendants of a class in Ruby
...e:
class Parent
def self.descendants
ObjectSpace.each_object(Class).select { |klass| klass < self }
end
end
class Child < Parent
end
class GrandChild < Child
end
puts Parent.descendants
puts Child.descendants
puts Parent.descendants gives you:
GrandChild
Child
puts Child.de...
How to uncheck a radio button?
...nt need the each function; you could just chain the removeAttr call to the selector.
– cjstehno
Jan 22 '10 at 13:55
6
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