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Reshaping data.frame from wide to long format
I have some trouble to convert my data.frame from a wide table to a long table.
At the moment it looks like this:
9 Answe...
What's the difference between session.Merge and session.SaveOrUpdate?
...n, do nothing
if another object associated with the session has the same identifier,
throw an exception
if the object has no identifier property, save() it
if the object's identifier has the value assigned to a newly
instantiated object, save() it
if the object is versioned (by a <v...
Nested attributes unpermitted parameters
...hing like
params.require(:person).permit(:name, :age, pets_attributes: [:id, :name, :category])
Some more details can be found in the Ruby edge API docs and strong_parameters on github or here
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PHP + MySQL transactions examples
...
The idea I generally use when working with transactions looks like this (semi-pseudo-code):
try {
// First of all, let's begin a transaction
$db->beginTransaction();
// A set of queries; if one fails, an excep...
Android getting value from selected radiobutton
...
Tested and working. Check this
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android....
How do I associate a Vagrant project directory with an existing VirtualBox VM?
...".vagrant" file in the same directory as your "Vagrantfile" to track the UUID of your VM. This file will not exist if a VM does not exist. The format of the file is JSON. It looks like this if a single VM exists:
{
"active":{
"default":"02f8b71c-75c6-4f33-a161-0f46a0665ab6"
}
}
defaul...
If threads share the same PID, how can they be identified?
...
The four threads will have the same PID but only when viewed from above. What you (as a user) call a PID is not what the kernel (looking from below) calls a PID.
In the kernel, each thread has it's own ID, called a PID (although it would possibly make more sens...
How do I use su to execute the rest of the bash script as that user?
...
I did this - but it still asked me for a password.
– Hippyjim
Oct 19 '13 at 16:30
...
Redis key naming conventions?
...s website is stated: Try to stick with a schema. For instance "object-type:id:field" can be
a nice idea, like in "user:1000:password". I like to use dots for
multi-words fields, like in "comment:1234:reply.to".
Are you able to query for just the beginning of the key to return all
users?
If y...
How to delete or add column in SQLITE?
...mplementation based on the Sqlite's recommended way to do this:
private void dropColumn(SQLiteDatabase db,
ConnectionSource connectionSource,
String createTableCmd,
String tableName,
String[] colsToRemove) throws java.sql.SQLException {
List<String> update...