Tutorial by Topics: es

The special symbol .SD is available in j of DT[i,j,by], capturing the Subset of Data for each by group surviving the filter, i. .SDcols is a helper. Type ?`special-symbols` for the official docs. A reminder: DT[where, select|update|do, by] syntax is used to work with columns of a data.table. T...

New versions of Ubuntu are released by Canonical every 6 months. Every two years, the release is a Long Term Support version. Support lifespan Normal release - supported for 9 months Long Term Support (LTS) release    • LTS releases for Ubuntu Desktop, Ubuntu Server, Ubuntu Core, and Ubuntu ...

$ shopt -u option # Deactivate Bash's built-in 'option' $ shopt -s option # Activate Bash's built-in 'option' Character Classes Valid character classes for the [] glob are defined by the POSIX standard: alnum alpha ascii blank cntrl digit graph lower print punct space upper word xdig...

There are many excellent reference and example sources on the Web. Some examples and explanations are created here as a collection point for quick answers. More detailed illustrations may be linked to external content (instead of copying existing original material).

git worktree add [-f] [--detach] [--checkout] [-b <new-branch>] <path> [<branch>] git worktree prune [-n] [-v] [--expire <expire>] git worktree list [--porcelain] ParameterDetails-f --forceBy default, add refuses to create a new working tree when <branch> is a...

Azure Service Fabric is one of the PaaS services offered by Azure. It is based on the notion of containers and services: unlike Compute services (Web Roles and Worker roles), your code does not run inside one (or more) Virtual Machines, but instead they are run inside a container, sharing it with...

std::atomic<T> std::atomic_flag std::atomic allows atomic access to a TriviallyCopyable type, it is implementation-dependent if this is done via atomic operations or by using locks. The only guaranteed lock-free atomic type is std::atomic_flag.

C# version 3.0 was released as part of .Net version 3.5. Many of the features added with this version were in support of LINQ (Language INtegrated Queries). List of added features: LINQ Lambda expressions Extension methods Anonymous types Implicitly typed variables Object and Collection I...

To run any of these examples just call them like that: static void Main() { new Program().ProcessDataAsync(); Console.ReadLine(); }

The ^M character stands for a carriage return in Vim (<c-m> or just <CR>). Vim displays this character when at least on line in the file uses LF line endings. In other words, when Vim consider a file to have fileformat=unix but some lines do have carriage returns (CR), the carriage r...

To avoid serialization problems, particularly in distributed environments (e.g. Apache Spark), it is a best practice to implement the Serializable trait for type class instances.

Session["Session_Key"] = Obj_Value; HTTP is stateless. ASP.NET session state is a framework that facilitates maintaining state between HTTP page requests. Session differs from the class level variables in its ability to remain available across post-backs and different pages. For ...

REST stands for Representational State Transfer (sometimes spelled "ReST"). It relies on a stateless, client-server, cacheable communications protocol and mostly HTTP protocol is used. It is primarily used to build Web services that are lightweight, maintainable, and scalable. A service ba...

template identifier (TemplateParameterList) { ... } struct identifier (TemplateParameterList) { ... } class identifier (TemplateParameterList) { ... } ReturnType identifier (TemplateParameterList)(ParameterList) { ... } identifier!(TemplateInvocationList)