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Differences in subsetting syntax A data.table is one of several two-dimensional data structures available in R, besides data.frame, matrix and (2D) array. All of these classes use a very similar but not identical syntax for subsetting, the A[rows, cols] schema. Consider the following data stored i...

Category theory is a modern mathematical theory and a branch of abstract algebra focused on the nature of connectedness and relation. It is useful for giving solid foundations and common language to many highly reusable programming abstractions. Haskell uses Category theory as inspiration for some o...

A category C consists of: A collection of objects called Obj(C) ; A collection (called Hom(C)) of morphisms between those objects. If a and b are in Obj(C), then a morphism f in Hom(C) is typically denoted f : a -> b, and the collection of all morphism between a and b is denoted hom(a,b) ; A...

Using Kestrel you can specify port using next approaches: Defining ASPNETCORE_URLS environment variable. Windows SET ASPNETCORE_URLS=https://0.0.0.0:5001 OS X export ASPNETCORE_URLS=https://0.0.0.0:5001 Via command line passing --server.urls parameter dotnet run --server.urls=http...

When configuring the built-in logging functionality, a common pattern is to create a logger with the __name__ of the current module: logger = logging.getLogger(__name__) This means that the fully-qualified name of the module will appear in the logs, making it easier to see where messages have co...

If you have a string that contains Python literals, such as strings, floats etc, you can use ast.literal_eval to evaluate its value instead of eval. This has the added feature of allowing only certain syntax. >>> import ast >>> code = """(1, 2, {'foo': 'bar'})&quot...

It is not possible to use eval or exec to execute code from untrusted user securely. Even ast.literal_eval is prone to crashes in the parser. It is sometimes possible to guard against malicious code execution, but it doesn't exclude the possibility of outright crashes in the parser or the tokenizer....

Detailed instructions on getting forms set up or installed.

Types instantiating Ord include, e.g., Int, String, and [a] (for types a where there's an Ord a instance). If a type instantiates Ord it means that we know a “natural” ordering of values of that type. Note, there are often many possible choices of the “natural” ordering of a type and Ord forces us t...

First of all, you cannot "install" Java EE. Java EE consists of a number of specifications. You can install implementations of those specifications however. Depending on your needs, there are lots of possibilities. To install most (or all) of the specifications, you can choose a Java EE...

You can select elements with different selectors : by tag : "div" by class : ".class" by id : "#id" by attribute : "[color=blue]" multiple selectors (OR): "div1, div2, class1" multiple selectors (AND): "div1 div2 class1"

This will give current system version. Objective-C NSString *version = [[UIDevice currentDevice] systemVersion] Swift let version = UIDevice.currentDevice().systemVersion Swift 3 let version = UIDevice.current.systemVersion

<div class="navbar navbar-inverse navbar-fixed-top"> <div class="container"> <div class="navbar-header"> <!--- vvv Hamburger icon that gets shown when window reaches a certain scale vvv ---> <button type...

You can choose between major distributions of LaTeX: TeX Live (Windows, Linux, and OS X), the standard, cross-platform distribution. MacTeX (Mac) A packaged version of TeX Live made for OS X with some Mac-specific tools MiKTeX (Windows) A separate distribution entirely that All distributions...

With ASP.NET Core 1.0, the MVC and Web API framework have been merged into one framework called ASP.NET Core MVC. This is a good thing, since MVC and Web API share a lot of functionality, yet there always were subtle differences and code duplication. However, merging these two into framework one ...

LOOP AT itab INTO wa. ENDLOOP. FIELD-SYMBOLS <fs> LIKE LINE OF itab. LOOP AT itab ASSIGNING <fs>. ENDLOOP. LOOP AT itab ASSIGNING FIELD-SYMBOL(<fs>). ENDLOOP. LOOP AT itab REFERENCE INTO dref. ENDLOOP. LOOP AT itab TRANSPORTING NO FIELDS. ENDLOOP. Conditional L...

In Scala operators (such as +, -, *, ++, etc.) are just methods. For instance, 1 + 2 can be written as 1.+(2). These sorts of methods are called 'infix operators'. This means custom methods can be defined on your own types, reusing these operators: class Matrix(rows: Int, cols: Int, val data: Seq[...

To make a custom pipe available application wide, During application bootstrap, extending PLATFORM_PIPES. import { bootstrap } from '@angular/platform-browser-dynamic'; import { provide, PLATFORM_PIPES } from '@angular/core'; import { AppComponent } from './app.component'; import { MyPipe }...

Detailed instructions on getting WSO2 set up or installed. Almost all the WSO2 Products can be started using the wso2server.sh/bat files that can be found in the <Product_Home>/bin folder of each product. When you run the sh/bat script it will star the particular WSO2 product with default set...

The case modifier causes the Scala compiler to automatically generate common boilerplate code for the class. Implementing this code manually is tedious and a source of errors. The following case class definition: case class Person(name: String, age: Int) ... will have the following code automati...