Tutorial by Topics: i

A reminder: DT[where, select|update|do, by] syntax is used to work with columns of a data.table. The "where" part is the i argument The "select|update|do" part is the j argument These two arguments are usually passed by position instead of by name.

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...

The sqlite3 command-line shell implements an additional set of commands (which are not available in programs that use the SQLite library). Official documentation: Special commands to sqlite3

Folding causes multiple lines of text to be collapsed and displayed as a single line. It is useful for hiding portions of a document considered unimportant for the current task. Folding is purely a visual change to the document: the folded lines are still present, unchanged. A fold is persistent....

public static GameObject Find(string name); public static GameObject FindGameObjectWithTag(string tag); public static GameObject[] FindGameObjectsWithTag(string tag); public static Object FindObjectOfType(Type type); public static Object[] FindObjectsOfType(Type type); Which method to...

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...

Entity Framework (EF) Core is a lightweight and extensible version of the popular Entity Framework data access technology. EF Core is an object-relational mapper (O/RM) that enables .NET developers to work with a database using .NET objects. It eliminates the need for most of the data-access code...

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).

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...

VHDL is a compound acronym for VHSIC (Very High Speed Integrated Circuit) HDL (Hardware Description Language). As a Hardware Description Language, it is primarily used to describe or model circuits. VHDL is an ideal language for describing circuits since it offers language constructs that easily d...

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.

if expression ... end if expression ... else ... end if expression ... elseif expression ... end if expression ... elseif expression ... else ... end ParameterDescriptionexpressionan expression that has logical meaning