evenpositioned

Evenpositioned is an adjective used to describe elements of a sequence that occupy even-numbered positions when the sequence is ordered. In mathematics and computing, this usually means positions 2, 4, 6, and so on. If the first element is considered position 1, the even-positioned elements are the second, fourth, sixth elements, etc.

Indexing conventions affect how “even-positioned” is interpreted. Some contexts, especially in programming, use zero-based indexing where the first element has index 0. In such cases, the even-positioned elements correspond to indices 0, 2, 4, and so forth. This distinction is important when implementing algorithms that select or manipulate even-positioned elements.

Examples and uses of the concept are common across data structures. For a list [a, b, c, d, e], the even-positioned elements (counting from 1) are b and d; the odd-positioned elements are a, c, and e. In data processing, operations often target even-positioned elements, such as summing every second item or applying filters to alternating items. In many programming languages, selecting even-positioned elements can be expressed with a slice or step of 2 starting at the appropriate offset.

The term applies to any ordered collection, including strings, arrays, rows in a table, or sequences in mathematics. The notion is purely positional and does not depend on the actual values, except for the indexing convention used to define which positions are even.