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27 Sets

Octave has a limited number of functions for managing sets of data, where a set is defined as a collection of unique elements. In Octave a set is represented as a vector of numbers.

Function File: unique (x)
Function File: unique (x, "rows")
Function File: unique (…, "first")
Function File: unique (…, "last")
Function File: [y, i, j] = unique (…)

Return the unique elements of x, sorted in ascending order. If the input x is a vector then the output is also a vector with the same orientation (row or column) as the input. For a matrix input the output is always a column vector. x may also be a cell array of strings.

If the optional argument "rows" is supplied, return the unique rows of x, sorted in ascending order.

If requested, return index vectors i and j such that x(i)==y and y(j)==x.

Additionally, if i is a requested output then one of "first" or "last" may be given as an input. If "last" is specified, return the highest possible indices in i, otherwise, if "first" is specified, return the lowest. The default is "last".

See also: union, intersect, setdiff, setxor, ismember.