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Position

FilledSmallSquare Position[expr, pattern] gives a list of the positions at which objects matching pattern appear in expr.

FilledSmallSquare Position[expr, pattern, levspec] finds only objects that appear on levels specified by levspec.

FilledSmallSquare Position[expr, pattern, levspec, n] gives the positions of the first n objects found.

FilledSmallSquare Example: Position[1+x^2, 5, x^4, x^_] LongRightArrow.

FilledSmallSquare Position[expr, pattern] tests all the subparts of expr in turn to try and find ones that match pattern.

FilledSmallSquare Position returns a list of positions in a form suitable for use in Extract, ReplacePart and MapAt. The form is different from the one used in Part.

FilledSmallSquare The default level specification for Position is {0, Infinity}, with Heads -> True.

FilledSmallSquare A part specification {} returned by Position represents the whole of expr.

FilledSmallSquare Position[list, pattern, 1, Heads -> False] finds positions only of objects that appear as complete elements of list.

FilledSmallSquare Level specifications are described in Section A.3.6.

FilledSmallSquare See Section 1.8.5, Section 2.1.7, Section 2.2.4 and Section 2.3.2.

FilledSmallSquare See also: Cases, Count, StringPosition, Ordering, SparseArray, ReplaceList, Insert, Delete.

FilledSmallSquare New in Version 1.

Further Examples