Tutorial by Examples: d

We can read from a text file: dt <- fread("my_file.csv") Unlike read.csv, fread will read strings as strings, not as factors by default. See the [topic on fread][need_a_link] for more examples.

For efficiency, data.table offers a way of altering a data.frame or list to make a data.table in-place: # example data.frame DF = data.frame(x = letters[1:5], y = 1:5, z = (1:5) > 3) # modification setDT(DF) Note that we do not <- assign the result, since the object DF has been modifi...

# example data DT1 = data.table(x = letters[1:2], y = 1:2, z = (1:2) > 3) Due to the way data.tables are manipulated, DT2 <- DT1 will not make a copy. That is, later modifications to the columns or other attributes of DT2 will affect DT1 as well. When you want a real copy, use DT2 = copy(...

# example data DT = data.table(Titanic) Suppose we want to see each class only if a majority survived: DT[, if (sum(N[Survived=="Yes"]) > sum(N[Survived=="No"]) ) .SD, by=Class] # Class Sex Age Survived N # 1: 1st Male Child No 0 # 2: 1st Fema...

Delete all nodes MATCH (n) DETACH DELETE n DETACH doesn't work in older versions(less then 2.3), for previous versions use MATCH (n) OPTIONAL MATCH (n)-[r]-() DELETE n, r Delete all nodes of a specific label MATCH (n:Book) DELETE n

Match (node_name:node_type {}), (node_name_two:node_type_two {}) CREATE (node_name)-[::edge_name{}]->(node_name_two)

The DISTINCT clause after SELECT eliminates duplicate rows from the result set. CREATE TABLE `car` ( `car_id` INT UNSIGNED NOT NULL PRIMARY KEY, `name` VARCHAR(20), `price` DECIMAL(8,2) ); INSERT INTO CAR (`car_id`, `name`, `price`) VALUES (1, 'Audi A1', '20000'); INSERT INTO CA...

Monotonic predicates can be debugged by applying declarative reasoning. In pure Prolog, a programming mistake can lead to one or all of the following phenomena: the predicate incorrectly succeeds in a case where it should fail the predicate incorrectly fails in a case where it should succeed t...

Examples of monotonic predicates are: unification with (=)/2 or unify_with_occurs_check/2 dif/2, expressing disequality of terms CLP(FD) constraints like (#=)/2 and (#>)/2, using a monotonic execution mode. Prolog predicates that only use monotonic goals are themselves monotonic. Monoton...

Here are examples of predicates that are not monotonic: meta-logical predicates like var/1, integer/1 etc. term comparison predicates like (@<)/2 and (@>=)/2 predicates that use !/0, (\+)/1 and other constructs that break monotonicity all-solutions predicates like findall/3 and setof/3. ...

//Example 1 int[] array = { 1, 5, 2, 10, 7 }; // Select squares of all odd numbers in the array sorted in descending order IEnumerable<int> query = from x in array where x % 2 == 1 orderby x descending select x ...

To interact with WebElements in a webpage, first we need to identify the location of the element. By is the keyword available in selenium. You can locate the elements By.. By ID By Class Name By TagName By Name By Link Text By Partial Link Text By CSS Selector By XPath Using JavaScript ...

Option Compare Binary Binary comparison makes all checks for string equality within a module/class case sensitive. Technically, with this option, string comparisons are performed using sort order of the binary representations of each character. A < B < E < Z < a < b < e < z ...

CSS div.needle { margin: 100px; height: 150px; width: 150px; transform: rotateY(85deg) rotateZ(45deg); /* presentational */ background-image: linear-gradient(to top left, #555 0%, #555 40%, #444 50%, #333 97%); box-shadow: inset 6px 6px 22px 8px #272727; } HTML <div c...

In general, UWP is used for making a single application that runs on Windows 10 across many different devices. However, it is also possible to make code tailored to specific devices. You can achieve this in several different ways. Different XAML Layout If you want to use a specific layout on for a...

The chan-signal crate provides a solution to handle OS signal using channels, altough this crate is experimental and should be used carefully. Example taken from BurntSushi/chan-signal. #[macro_use] extern crate chan; extern crate chan_signal; use chan_signal::Signal; fn main() { // S...

The nix crate provides an UNIX Rust API to handle signals, however it requires using unsafe rust so you should be careful. use nix::sys::signal; extern fn handle_sigint(_:i32) { // Be careful here... } fn main() { let sig_action = signal::SigAction::new(handle_sigint, ...

Unlike emails, JIDs were defined with Internationalization (i18n) in mind using the Preparation, Enforcement, and Comparison of Internationalized Strings (PRECIS) framework. PRECIS (defined in RFC 7564), is a framework for comparing strings safely in a variety of contexts. For instance, imagine you...

Adding a footer is not natively possible. Luckily, we can make use of jQuery and CSS to add a footer to the slides of an ioslides presentation rendered with knitr. First of all we have to include the jQuery plugin. This is done by the line <script src="https://ajax.googleapis.com/ajax/libs...

A very basic docker-compose.yml looks like this: version: '2' services: hello_world: image: ubuntu command: [/bin/echo, 'Hello world'] This file is making it so that there's a hello_world service, that's initialized from the ubuntu:latest image and that, when it's run, it just runs...