Tutorial by Examples: c

Take a use case, like a chat app or a collaborative grocery list app (that basically requires a list of objects to be synced across users). If you use firebase database and add a value event listener to the chat parent node or grocery list parent node, you will end with entire chat structure from th...

In [1]: df = pd.DataFrame({'A': [1, 2, 3], 'B': [1.0, 2.0, 3.0], 'C': ['a', 'b', 'c'], 'D': [True, False, True]}) In [2]: df Out[2]: A B C D 0 1 1.0 a True 1 2 2.0 b False 2 3 3.0 c True Getting a python list from a series: In [3]: df['...

Magento is a very popular eCommerce application. It offers a great deal of customization and abilities from initial install. Here are a few suggestions for optimizing a Magento installation. Enabling Output Compression In your .htaccess file for Magento you will find a section of text starting wit...

The model Magento uses to store customer and product data results in longer than average SQL queries and more reads. Enabling the Flat Catalog option for Categories and Products will merge product data into one table, therefore improving performance. Login to your administration area and go to – Sy...

Login to your administration area and go to – System > Cache Management Next, click on the Select All link Finally, make sure the Actions is set to Enable and click submit Disable Error Logging Login to your administration area and go to – System > Configuration > Developer Under ...

The task is to find the length of the longest subsequence in a given array of integers such that all elements of the subsequence are sorted in ascending order. For example, the length of the longest increasing subsequence(LIS) for {15, 27, 14, 38, 26, 55, 46, 65, 85} is 6 and the longest increasing ...

Cards are a great way to display important pieces of content, and are quickly emerging as a core design pattern for apps. They're are a great way to contain and organize information, while also setting up predictable expectations for the user. With so much content to display at once, and often so li...

Given a string what is the longest palindromic subsequence(LPS) of it? Let's take a string agbdba. The LPS of this string is abdba of length 5. Remember, since we're looking for subsequence, the characters need not to be continuous in the original string. The longest palindromic substring of the seq...

In order to search for packages in the databse, searching both in packages' names and descriptions: pacman -Ss string1 string2 ... To install a single package or list of packages (including dependencies), issue the following command: sudo pacman -S package_name1 package_name2 ... source

This chapter describes how to set up a Docker Container with Jenkins inside, which is capable of sending Docker commands to the Docker installation (the Docker Daemon) of the Host. Effectively using Docker in Docker. To achieve this, we have to build a custom Docker Image which is based on an arbitr...

Given coins of different denominations and a total, how many coins do we need to combine to get the total if we use minimum number of coins? Let's say we have coins = {1, 5, 6, 8} and a total = 11, we can get the total using 2 coins which is {5, 6}. This is indeed the minimum number of coins require...

You can configure Mail by just adding/changing these lines in the app's .ENV file with your email provider login details, for example for using it with gmail you can use: MAIL_DRIVER=smtp MAIL_HOST=smtp.gmail.com MAIL_PORT=587 [email protected] MAIL_PASSWORD=yourPassword MAIL_E...

You can also use this code to setup an LED with a button switch with a pull up resistor, this could preferably be with the next step after setting up the intial LED controller int buttonState = 0; // variable for reading the pushbutton status void setup() { // initialize the LED pin as an ...

Joda-Time is a robust alternative to the Java date and time classes. Prior to Java SE 8, the standard Java date and time classes like java.util.Calendar are difficult to use and prone to errors. Joda-Time emerged as the de-facto standard library for date and time manipulation in many open-source-pr...

The caching problem arises from the limitation of finite space. Lets assume our cache C has k pages. Now we want to process a sequence of m item requests which must have been placed in the cache before they are processed.Of course if m<=k then we just put all elements in the cache and it will wo...

This is an example of a web-socket client in javascript. It: Connects to a live demo server. Sends a message. Receives message(s). Disconnects after an interval. var mySocket = null; var serverUrl = 'wss://echo.websocket.org'; // wss: is ws: but using SSL. var oWebSocket = window...

Adding the aurelia-configuration to a cli application sometimes produces a build error. This is caused by a missing dependency so we simply add the dependency to the build bundle. Try the following: npm install deep-extend --save npm install aurelia-configuration --save Now add the followi...

It's also possible to add multiple object types to a Static Dispatch function. fn mammal_speak<T: Person + Dog>(mammal: &T) { println!("{0}", mammal.speak()); } fn main() { let person = Person {}; let dog = Dog {}; mammal_speak(&person); mammal...

Two-element tuples (,) is an example of a type that has a Bifunctor instance. instance Bifunctor (,) where bimap f g (x, y) = (f x, g y) bimap takes a pair of functions and applies them to the tuple's respective components. bimap (+ 2) (++ "nie") (3, "john") --> (5,...

If mapping covariantly over only the first argument, or only the second argument, is desired, then first or second ought to be used (in lieu of bimap). first :: Bifunctor f => (a -> c) -> f a b -> f c b first f = bimap f id second :: Bifunctor f => (b -> d) -> f a b -> f...