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Selecting only numeric columns from a data frame
...traightforward, and robust to use on database-back-ended tibbles:
dplyr::select_if(x, is.numeric)
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MySQL error: key specification without a key length
...d, and the trick is to choose a number N that’s long enough to give good selectivity, but short enough to save space. The prefix should be long enough to make the index nearly as useful as it would be if you’d indexed the whole column.
Before we go further let us define some important terms. In...
Only one expression can be specified in the select list when the subquery is not introduced with EXI
...column on the other side of the IN. So the query needs to be of the form:
SELECT * From ThisTable WHERE ThisColumn IN (SELECT ThatColumn FROM ThatTable)
You also want to add sorting so you can select just from the top rows, but you don't need to return the COUNT as a column in order to do your so...
How do I view the type of a scala expression in IntelliJ
...
Select expression and type Alt + =.
If you want to change the shortcut go to Preferences > Keymap and enter "Type Info" in the search field.
In older versions, it's Shift + Ctrl + Alt + T.
...
What's the equivalent for eclipse's ALT+UP/DOWN (move line) in Visual Studio?
In Eclipse, selecting a line and pressing Alt + ↑ / ↓ will move the line up and down, a quick way to avoid copy&paste.
Is there an equivalent in Visual Studio?
...
How to call Android contacts list?
...TION_PICK on the People.CONTENT_URI, then return to this Activity when the selection is made (or canceled).
startActivityForResult(intent, PICK_CONTACT);
3. Listening for the Result
Also in your Activity, override the onActivityResult method to listen for the return from the 'select a contact' A...
How do I delete NuGet packages that are not referenced by any project in my solution?
...
First open the Package Manager Console. Then select your project from the dropdown list. And run the following commands for uninstalling nuget packages.
Get-Package
for getting all the package you have installed.
and then
Uninstall-Package PagedList.Mvc
--- to unin...
Generating random strings with T-SQL
...st varchar(8000)
declare @step bigint = rand(@seed) * 2147483647;
select @alpha = 'qwertyuiopasdfghjklzxcvbnm'
, @digit = '1234567890'
, @specials = '_@# '
select @first = @alpha + '_@';
set @seed = (rand((@seed+@step)%2147483647)*2147483647);
select @length =...
How to join int[] to a character separated string in .NET?
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var ints = new int[] {1, 2, 3, 4, 5};
var result = string.Join(",", ints.Select(x => x.ToString()).ToArray());
Console.WriteLine(result); // prints "1,2,3,4,5"
EDIT: As of (at least) .NET 4.5,
var result = string.Join(",", ints.Select(x => x.ToString()).ToArray());
is equivalent to:
v...
Best way to add Activity to an Android project in Eclipse?
...th Eclipse 3.5.2 on Ubuntu 10.04. When the add dialog comes up, it has two selections... No, now only one "Create a new element at the top level, in Application." Ne;low that there is a text entry field and below that, a box with selections for Activity, Activity Alias, Meta Data and so on. Below th...