Tutorial by Examples: b

The [ and [[ operators are primitive functions that are generic. This means that any object in R (specifically isTRUE(is.object(x)) --i.e. has an explicit "class" attribute) can have its own specified behaviour when subsetted; i.e. has its own methods for [ and/or [[. For example, this is...

Lazy evaluation means Haskell will evaluate only list items whose values are needed. The basic recursive definition is: f (0) <- 0 f (1) <- 1 f (n) <- f (n-1) + f (n-2) If evaluated directly, it will be very slow. But, imagine we have a list that records all the results, fibs ...

First, instantiate a Toast object with one of the MakeText() methods. This method takes three parameters: the application Context, the text message, and the duration for the toast. It returns a properly initialized Toast object. You can display the toast notification with Show(), as shown in the fol...

Behavior Driven Development (BDD) testing style revolves around "given", "when" and "then" stages in tests. However, classical Mockito uses "when" word for "given" phase, and does not include other natural language constructions that can encompass B...

There is no simple way to obtain attributes from an interface, since classes does not inherit attributes from an interface. Whenever implementing an interface or overriding members in a derived class, you need to re-declare the attributes. So in the example below output would be True in all three c...

In this example our project name is "helloworld" which was created with stack new helloworld simple First we have to build the project with stack build and then we can run it with stack exec helloworld-exe

The code below implements a very simple complex number type for which the underlying field is automatically promoted, following the language's type promotion rules, under application of the four basic operators (+, -, *, and /) with a member of a different field (be it another complex<T> or so...

def foo(li=[]): li.append(1) print(li) foo([2]) # Out: [2, 1] foo([3]) # Out: [3, 1] This code behaves as expected, but what if we don't pass an argument? foo() # Out: [1] As expected... foo() # Out: [1, 1] Not as expected... This is because default arguments of function...

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Use in operator to check if an element is a member of a list. iex> 2 in [1, 2, 3] true iex> "bob" in [1, 2, 3] false

Common use when: ansible_os_family == "CentOS" when: ansible_os_family == "Redhat" when: ansible_os_family == "Darwin" when: ansible_os_family == "Debian" when: ansible_os_family == "Windows" All Lists based on discuss here http://comments...

Directives can be used to build reusable components. Here is an example of a "user box" component: userBox.js angular.module('simpleDirective', []).directive('userBox', function() { return { scope: { username: '=username', reputation: '=reputation' }, ...

The angular.isObject return true if and only if the argument passed to it is an object, this function will also return true for an Array and will return false for null even though typeof null is object . angular.isObject(value) This function is useful for type checking when you need a defined ...

Create a group of checkboxes that can be used to toggle multiple choices independently. The server will receive the input as a character vector of the selected values. library(shiny) ui <- fluidPage( checkboxGroupInput("checkGroup1", label = h3("This is a Checkbox group&...

In order to ssh into a server your identity's public key has to be added to the list of trusted keys. Most commonly this is done per-user: ssh-copy-id -i ~/.ssh/<identity>.pub <user>@<hostname> Which can be also done manually: cat ~/.ssh/<identity>.pub | ssh <user>...

Many people don't make use of file.path when making path to a file. But if you are working across Windows, Mac and Linux machines it's usually good practice to use it for making paths instead of paste. FilePath <- file.path(AVariableWithFullProjectPath,"SomeSubfolder","SomeFileNam...

Problem: When you use many labels inside a view, you maybe get a warning: How can we fix this warning? Solution: We calculate and set the priorities in order. The priorities must be different from labels. It means which is important will get higher priority. For example, in my case, I set the ve...

Often in R you'll want to know things about an object or variable you're working with. This can be useful when reading someone else's code or even your own, especially when using packages that are new to you. Suppose we create a variable a: a <- matrix(1:9, 3, 3) What data type is this? Yo...

In this exercise, we will generate four bootstrap linear regression models and combine the summaries of these models into a single data frame. library(broom) #* Create the bootstrap data sets BootData <- lapply(1:4, function(i) mtcars[sample(1:nrow(mtcars), ...

Derives from Object Key members public Dispatcher Dispatcher { get; } Summary Most objects in WPF derive from DispatcherObject, which provides the basic constructs for dealing with concurrency and threading. Such objects are associated with a Dispatcher. Only the thread that the Dispatcher w...