PositionSorted( list, elm )
PositionSorted( list, elm, func )
In the first form PositionSorted
returns the position of the element
elm, which may be an object of any type, with respect to the sorted
list list.
In the second form PositionSorted
returns the position of the element
elm, which may be an object of any type with respect to the list
list, which must be sorted with respect to func. func must be a
function of two arguments that returns true
if the first argument is
less than the second argument and false
otherwise.
PositionSorted
returns pos such that list[pos-1] < elm
and
elm <= list[pos]
. That means, if elm appears once in list,
its position is returned. If elm appears several times in list, the
position of the first occurrence is returned. If elm is not an element
of list, the index where elm must be inserted to keep the list sorted
is returned.
gap> PositionSorted( [1,4,5,5,6,7], 0 ); 1 gap> PositionSorted( [1,4,5,5,6,7], 2 ); 2 gap> PositionSorted( [1,4,5,5,6,7], 4 ); 2 gap> PositionSorted( [1,4,5,5,6,7], 5 ); 3 gap> PositionSorted( [1,4,5,5,6,7], 8 ); 7
Position
(see Position) is another function that returns the position
of an element in a list. Position
accepts unsorted lists, uses linear
instead of binary search and returns false
if elm is not in list.
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GAP 3.4.4