Vector Type

Any one of the six basic forms the elements in an atomic vector can take. The four types we will encounter the most are: double, integer, character and logical.


The process of changing a vector from one type to another. Sometimes the process takes place automatically, as a convenience to the programmer.


The operation of selecting one or more elements from a vector.


An automatic process by which R, when given two vectors, repeats elements of the shorter vector until it is as long as the longer vector. Recycling enables the two resulting vectors to be combined element-wise in operations.


R’s ability to operate on each element of a vector, producing a new vector of the same length. Vectorized operations can be expressed concisely and performed very quickly.

Reserved Words

Identifiers that are set aside by R for specific programming purposes. They cannot be used as names of variables.


The complete set of rules for a computer language that determine what combinations of symbols are considered to make a well-formed program in the language.

Syntax Error

A sequence of symbols that contains a violation of one of the rules of syntax. R is unable to interpret and attempt to execute code that contains a syntax error.

Run-time Error

An error that occurs when the computer language’s interpreter attempts to execute code but is unable to do so. A typical cause of a run-time error is the situation when the code calls for the evaluation of a name that has not been bound to an object.

Semantic Error

An error in code that is syntactically correct and that can be executed by the computer but which produces unexpected results.