Tutorial by Examples: nd

To improve performance one might want to add indexes to columns ALTER TABLE TABLE_NAME ADD INDEX `index_name` (`column_name`) altering to add composite (multiple column) indexes ALTER TABLE TABLE_NAME ADD INDEX `index_name` (`col1`,`col2`)

The AUROC is one of the most commonly used metric to evaluate a classifier's performances. This section explains how to compute it. AUC (Area Under the Curve) is used most of the time to mean AUROC, which is a bad practice as AUC is ambiguous (could be any curve) while AUROC is not. Overview – Abb...

A compound literal is an unnamed object which is created in the scope where is defined. The concept was first introduced in C99 standard. An example for compound literal is Examples from C standard, C11-§6.5.2.5/9: int *p = (int [2]){ 2, 4 }; p is initialized to the address of the first ele...

Using the Library Database, we try to find the last book added to the database for each author. For this simple example we assume an always incrementing Id for each record added. SELECT MostRecentBook.Name, MostRecentBook.Title FROM ( SELECT Authors.Name, Books.Title, ...

As of Qt 5.1 and later you can use QQmlApplicationEngine instead of QQuickView to load and render a QML script. With QQmlApplicationEngine you do need to use a QML Window type as your root element. You can obtain the root context from the engine where you can then add global properties to the cont...

>>> df ID Year Jan_salary Feb_salary Mar_salary 0 1 2016 4500 4200 4700 1 2 2016 3800 3600 4400 2 3 2016 5500 5200 5300 >>> melted_df = pd.melt(df,id_vars=['ID','Year'], v...

Example for searching just one user with a specific id, you should do: $options = ['limit' => 1]; $filter = ['_id' => new \MongoDB\BSON\ObjectID('578ff7c3648c940e008b457a')]; $query = new \MongoDB\Driver\Query($filter, $options); $cursor = $manager->executeQuery('database_name.collect...

Example for searching multiple users with the name "Mike": $filter = ['name' => 'Mike']; $query = new \MongoDB\Driver\Query($filter); $cursor = $manager->executeQuery('database_name.collection_name', $query); foreach ($cursor as $doc) { var_dump($doc); }

Navigation Drawers are used to navigate to top-level destinations in an app. Make sure that you have added design support library in your build.gradle file under dependencies: dependencies { // ... compile 'com.android.support:design:25.3.1' } Next, add the DrawerLayout and Navigati...

Comments are used to explain code when the basic code itself isn't clear. Python ignores comments, and so will not execute code in there, or raise syntax errors for plain english sentences. Single-line comments begin with the hash character (#) and are terminated by the end of line. Single lin...

auto can also cause problems where expression templates come into play: auto mult(int c) { return c * std::valarray<int>{1}; } auto v = mult(3); std::cout << v[0]; // some value that could be, but almost certainly is not, 3. The reason is that operator* on valarray gives yo...

Detailed instructions on getting mule set up or installed. Before going to start with mule we have to insure that java home is set. Mule CE runtime don't need installation. We have to just unzip the downloaded file and go to bin directory of mule runtime. In MS windows Operating system we have...

Usually grep prints only matching lines. In the example below seq 9 generates a list of numbers from 1 to 9, one per line, and grep prints a single matching line: seq 9 | grep 5 # 5 The -C n option (or --context=n in long form) prints n lines before and after each matching line, in addition to ...

Why an Editor Window? As you may have seen, you can do a lot of things in a custom inspector (if you don't know what a custom inspector is, check the example here : http://www.riptutorial.com/unity3d/topic/2506/extending-the-editor. But at one point you may want to implement a configuration panel, ...

Notice, that in order to change file prmissions, your device need to be rooted, su binary doesn't come with factory shipped devices! Convention: adb shell su -c "chmod <numeric-permisson> <file>" Numeric permission constructed from user, group and world sections. For exa...

Here is a tested code for image and video.It will work for all APIs less than 19 and greater than 19 as well. Image: if (Build.VERSION.SDK_INT <= 19) { Intent i = new Intent(); i.setType("image/*"); i.setAction...

If you just want to get data, but not modify anything, you can turn off change tracking and proxy creation. This will improve your performance and also prevent lazy loading. Bad Example: using(var context = new Context()) { return await context.Set<MyEntity>().ToListAsync().ConfigureAw...

The Preview pane displays default values for data binding expressions if provided. For example : android:layout_height="@{@dimen/main_layout_height, default=wrap_content}" It will take wrap_content while designing and will act as a wrap_content in preview pane. Another example i...

The alert method displays a visual alert box on screen. The alert method parameter is displayed to the user in plain text: window.alert(message); Because window is the global object, you can call also use the following shorthand: alert(message); So what does window.alert() do? Well, let's ta...

public class VolleyErrorHelper { /** * Returns appropriate message which is to be displayed to the user * against the specified error object. * * @param error * @param context * @return */ public static String ...