Array: Difference between revisions
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Common operations defined on arrays include:
* Indexing: accessing an array element by its indices. (There is a one to one mapping between an index and its corresponding element). While the cost of indexing is O(1) on typical current machines, the cost of indexing an element adjacent to a recently accessed element is much faster than indexing an arbitrary random element of a large array.
* Slicing: producing a subarray by putting some constraint on the indices. For example, [[PL/1]] provides extracting of a row or a column of an array. In [[Ada]] any range of the index can be used in order to extract a subarray from a single-dimensional array. In [[Python]] slices can extract any contiguous subset of an array and extended slice notation can extract elements in reversed order and/or by traversing in a given "stride" --- for example ''a[100:0:-2]'' would return every odd element from 100 to the beginning of the list: a[99], a[97], ... a[1].
* Iteration over the array's elements. Some languages make this a universal or implicit operation, some languages have a [[Loop/Foreach|foreach loop]] construct for array iteration, in others this must be done with conventional looping and arithmetic.
* Iteration over the indices of an associative or sparse array.
* Querying the bounds of array indices (determining the maximum element index of offset)
* Querying the indices of an associative array (determining if the collection contains a value for any given key).
* Operations on indices (next, previous, range etc)
* Sorting the contents of the array to satisfy some relationship.
* Array programming languages provide operations applied to entire arrays, so programs in such languages often lack specific index reference (for example [[APL]]).▼
* Searching an array for the location(s) of some value(s)
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Multidimensional arrays in which the valid range of one index depends on the value of another are called '''ragged''' (also '''jagged'''). This term comes from a typical example of a ragged array, when a two-dimensional array is used to store strings of different length in its rows. When put on paper the right margin of the output become ''ragged''.
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==Computational metrics==
Access is O(1), appending is O(1), and insertion is O(n) for a single item.
==Examples==
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