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Convert column classes in data.table
...)
Classes ‘data.table’ and 'data.frame': 10 obs. of 3 variables:
$ ID : Factor w/ 2 levels "A","B": 1 1 1 1 1 2 2 2 2 2
$ Quarter: chr "1" "2" "3" "4" ...
$ value : num -0.838 0.146 -1.059 -1.197 0.282 ...
Using lapply and as.character:
dtnew <- dt[, lapply(.SD, as.character...
How do I execute inserts and updates in an Alembic upgrade script?
...ly straightforward to adapt this to the other forms.
Note that Alembic provides some basic data functions: op.bulk_insert() and op.execute(). If the operations are fairly minimal, use those. If the migration requires relationships or other complex interactions, I prefer to use the full power of mo...
What's the $unwind operator in MongoDB?
...f adding and obtaining the data from your storage locations.
That being said, in order to understand the concept behind the $unwind parameter, you first must understand what the use case that you are trying to quote is saying. The example document from mongodb.org is as follows:
{
title : "this i...
How do I use Linq to obtain a unique list of properties from a list of objects?
I'm trying to use Linq to return a list of ids given a list of objects where the id is a property. I'd like to be able to do this without looping through each object and pulling out the unique ids that I find.
...
How to make ng-repeat filter out duplicate results
...e('yourModule', ['ui', 'ui.filters']);. Was stumped until I took a look inside the AngularUI js file.
– GFoley83
Apr 27 '13 at 4:45
...
Is having an 'OR' in an INNER JOIN condition a bad idea?
...tsets:
SELECT *
FROM maintable m
JOIN othertable o
ON o.parentId = m.id
UNION
SELECT *
FROM maintable m
JOIN othertable o
ON o.id = m.parentId
, each of them being an equijoin, however, SQL Server's optimizer is not smart enough to see it in the query you wrote (though the...
Detecting which UIButton was pressed in a UITableView
...ion:@selector(checkButtonTapped:) forControlEvents:UIControlEventTouchUpInside];
Then in touch handler touch coordinate retrieved and index path is calculated from that coordinate:
- (void)checkButtonTapped:(id)sender
{
CGPoint buttonPosition = [sender convertPoint:CGPointZero toView:self.ta...
Spring boot @ResponseBody doesn't serialize entity id
...rating an app to Spring Boot, I have observed that entity properties with @Id are no longer marshalled to JSON
To customize how it behaves, you can extend RepositoryRestConfigurerAdapter to expose IDs for specific classes.
import org.springframework.context.annotation.Configuration;
import org.spr...
How can I take more control in ASP.NET?
...tForm.aspx" method="get">
<div>
<input type="text" ID="text1" runat="server" />
<input type="text" ID="text2" runat="server" />
<button type="submit">Submit</button>
<asp:Repeater ID="Repeater1" runat="server">
&l...
Adding an identity to an existing column
I need to change the primary key of a table to an identity column, and there's already a number of rows in table.
19 Answe...