Tutorial by Examples: v

Consider the following tough-to-vectorize for loop, which creates a vector of length len where the first element is specified (first) and each element x_i is equal to cos(x_{i-1} + 1): repeatedCosPlusOne <- function(first, len) { x <- numeric(len) x[1] <- first for (i in 2:len) { ...

If you are using the default bash prompt on Linux, you should see the name of the virtual environment at the start of your prompt. (my-project-env) user@hostname:~$ which python /home/user/my-project-env/bin/python

In order to specify which version of python the Linux shell should use the first line of Python scripts can be a shebang line, which starts with #!: #!/usr/bin/python If you are in a virtual environment, then python myscript.py will use the Python from your virtual environment, but ./myscript.py...

In Rails, you find yourself looking at controllers, views, and models for your database. To reduce the need for heavy configuration, Rails implements rules to ease up working with the application. You may define your own rules but for the beginning (and for later on) it's a good idea to stick to co...

The default value for an enum is zero. If an enum does not define an item with a value of zero, its default value will be zero. public class Program { enum EnumExample { one = 1, two = 2 } public void Main() { var e =...

Now that the routes are set up, we need some way to actually change routes. This example will show how to change routes using the template, but it is possible to change routes in TypeScript. Here is one example (without binding): <a routerLink="/home">Home</a> If the user...

docker rm can be used to remove a specific containers like this: docker rm <container name or id> To remove all containers you can use this expression: docker rm $(docker ps -qa) By default docker will not delete a container that is running. Any container that is running will produce a...

execute the following command to insert the text into a view with a focus (if it supports text input) 6.0 Send text on SDK 23+ adb shell "input keyboard text 'Paste text on Android Device'" If already connected to your device via adb: input text 'Paste text on Android Device' 6...

A one-liner that helps granting or revoking vulnerable permissions. granting adb shell pm grant <sample.package.id> android.permission.<PERMISSION_NAME> revoking adb shell pm revoke <sample.package.id> android.permission.<PERMISSION_NAME> Granting all run...

It is common to want two views to be side by side, centered in their superview. The common answer given on Stack Overflow is to embed these two views in a UIView and center the UIView. This is not necessary or recommended. From the UILayoutGuide docs: There are a number of costs associated with...

Python supports using a for loop directly on a list: my_list = ['foo', 'bar', 'baz'] for item in my_list: print(item) # Output: foo # Output: bar # Output: baz You can also get the position of each item at the same time: for (index, item) in enumerate(my_list): print('The item i...

Class based views let you focus on what make your views special. A static about page might have nothing special, except the template used. Use a TemplateView! All you have to do is set a template name. Job done. Next. views.py from django.views.generic import TemplateView class AboutView(Tem...

Template views are fine for static page and you could use them for everything with get_context_data but it would be barely better than using function as views. Enter ListView and DetailView app/models.py from django.db import models class Pokemon(models.Model): name = models.CharField(max...

Following the Rcpp example in this documentation entry, consider the following tough-to-vectorize function, which creates a vector of length len where the first element is specified (first) and each element x_i is equal to cos(x_{i-1} + 1): repeatedCosPlusOne <- function(first, len) { x <-...

It is possible to configure Django to output log to a local or remote syslog service. This configuration uses the python builtin SysLogHandler. from logging.handlers import SysLogHandler LOGGING = { 'version': 1, 'disable_existing_loggers': True, 'formatters': { 'standard':...

A Traversal' s a shows that s has 0-to-many as inside of it. toListOf :: Traversal' s a -> (s -> [a]) Any type t which is Traversable automatically has that traverse :: Traversal (t a) a. We can use a Traversal to set or map over all of these a values > set traverse 1 [1..10] [1,1,1,...

This type of testing is popular technique for testing with predefined input and output values. Create a file called main.go with content: package main import ( "fmt" ) func main() { fmt.Println(Sum(4, 5)) } func Sum(a, b int) int { return a + b } After you r...

Using Playground it is easy to see that happens inside loops or objects while the change is happening. For example, in the code below, the value of x will change from 1 to 4. import UIKit for x in [1, 2, 3, 4] { x } (1) Clicking on the eye symbol on the right will give us a quick look. (2...

The standard ADB configuration involves a USB connection to a physical device. If you prefer, you can switch over to TCP/IP mode, and connect ADB via WiFi instead. Not rooted device Get on the same network: Make sure your device and your computer are on the same network. Connect the...

Variadic Arguments