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Select multiple columns in data.table by their numeric indices
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For versions of data.table >= 1.9.8, the following all just work:
library(data.table)
dt <- data.table(a = 1, b = 2, c = 3)
# select single column by index
dt[, 2]
# b
# 1: 2
# select multiple columns by index
dt[, 2:3]
# b c
# 1: 2 3
# select single column by na...
Why use 'git rm' to remove a file instead of 'rm'?
...ml
rm 'index.html'
$ git status -s
D index.html
However you can do this all in one go with just git rm
$ git status -s
$ git rm index.html
rm 'index.html'
$ ls
lib vendor
$ git status -s
D index.html
share
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What is the meaning of the planned “private protected” C# access modifier?
As part of the Roslyn documentation on GitHub, there's a page called Language feature implementation status , with planned language features for C# and VB.
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Ruby Regexp group matching, assign variables on 1 line
...u can use String#match which will return a MatchData object, you can then call #captures to return an Array of captures. Something like this:
#!/usr/bin/env ruby
string = "RyanOnRails: This is a test"
one, two, three = string.match(/(^.*)(:)(.*)/i).captures
p one #=> "RyanOnRails"
p two #=...
Remove blank attributes from an Object in Javascript
How do I remove all attributes which are undefined or null in a JavaScript object?
37 Answers
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Align button at the bottom of div using CSS
...e sure the content div is positioned.
To make the content div positioned, all position values that aren't static will work, but relative is the easiest since it doesn't change the divs positioning by itself.
So add position:relative; to the content div, remove the float from the button and add the...
Routing: The current request for action […] is ambiguous between the following action methods
I have a View called Browse.chtml , where the user can enter a search term, or leave the search term blank. When entering the search term, I want to direct the page to http://localhost:62019/Gallery/Browse/{Searchterm} and when nothing is entered, I want to direct the browser to http://localho...
How do I access the request object or any other variable in a form's clean() method?
... but how can I access the request object? Can I modify the clean method to allow variables input?
11 Answers
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Switch case with fallthrough?
I am looking for the correct syntax of the switch statement with fallthrough cases in Bash (ideally case-insensitive).
In PHP I would program it like:
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Re-entrant locks in C#
.....} is shorthand for using the Monitor class. As Marc points out, Monitor allows re-entrancy, so repeated attempts to lock on an object on which the current thread already has a lock will work just fine.
If you start locking on different objects, that's when you have to be careful. Pay particular ...